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IC 9134 



Bureau of Mines Information Circular/1987 



Mining Applications of Life Support 
Technology 

Proceedings: Bureau of Mines Technology Transfer 
Seminar, Pittsburgh, PA, November 20, 1986 



Compiled by Staff, Mining Research 




UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 9134 

Mining Applications of Life Support 
Technology 

Proceedings: Bureau of Mines Technology Transfer 
Seminar, Pittsburgh, PA, November 20, 1986 

Compiled by Staff, Mining Research 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Donald Paul Hodel, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 





WV 






>0 



) 



Library of Congress Cataloging in Publication Data: 



Bureau of Mines Technology Transfer Seminar (1986: Pittsburgh, Pa.) 
Mining applications of life support technology. 

(Information circular/United States Department of the Interior, Bureau of Mines; 9134) 

Includes bibliographies. 

Supt. of Docs, no.: I 28.27: 9134. 

1. Mine rescue work - Congresses. I. United States. Bureau of Mines. II. Title. III. Series: 
Information circular (United States. Bureau of Mines); 9134. 



--TN95.-U4 



[TN297] 



622 s 



[622'.8] 



86-607916 



PREFACE 

The papers contained in this Information Circular reflect the results 
of a Bureau of Mines research effort to improve life support technology 
used by the mining industry. The papers provide practical, up-to-date 
information concerning the use of mine rescue breathing apparatus and 
improved equipment for mine rescue teams. Such information can posi- 
tively impact the mining community by enhancing mine workers' chances of 
surviving an underground mine disaster. 

The seven papers were presented at a technology transfer seminar on 
mining applications of life support technology in November 1986. Tech- 
nology transfer seminars represent a major portion of the Bureau's tech- 
nology transfer program, which is designed to bring useful research re- 
sults to industry's attention so that they can be adopted without delay. 
Those desiring further information about developments resulting from 
other Bureau research programs should contact the Bureau of Mines, 
Branch of Technology Transfer, 2401 E St., NW, Washington, DC 20241. 



CONTENTS 



Page 



Preface i 

Abstract 1 

Introduction 2 

Overview of life support escape breathing apparatus technology, by John G. 

Kovac and Nicholas Kyriazi 3 

Problems in donning self-contained self -rescuers , by Charles Vaught and 

Henry P. Cole 26 

Physiology of mine escape: Performance decrements due to resistance breathing 

during three exercise protocols, by Kurt Saupe and Eliezer Kamon 35 

Second-generation self-contained self -rescuers, by John G. Kovac 39 

Development of a low-profile rescue breathing apparatus and a mine rescue team 

helmet , by Nicholas Kyriazi 47 

Training in the use of the self-contained self-rescuer, by Henry P. Cole and 

Charles Vaught 51 

Abstract of "Development of an automated breathing and metabolic simulator," 

by Nicholas Kyriazi (Information Circular 9110) 57 







UNIT OF MEASURE 


ABBREVIATIONS 


USED IN THIS 


REPORT 


°c 




degree Celsius 


lb 


pound 


cm 




centimeter 




m 


meter 


cu 


in 


cubic inch 




mi/h 


mile per hour 


h 




hour 




min 


minute 


in 




inch 




mm 


millimeter 


kg 




kilogram 




ms 


millisecond 


L 




liter 




s 


second 


L/min 


liter per minute 


yr 


year 



MINING APPLICATIONS OF LIFE SUPPORT TECHNOLOGY 



Proceedings: Bureau of Mines Technology Transfer 
Seminar, Pittsburgh, PA, November 20, 1986 



Compiled by Staff, Mining Research 



ABSTRACT 

The Bureau of Mines has conducted considerable research to improve 
life support technology for underground mining applications. This pro- 
ceedings volume presents several new developments that may help increase 
the chances of mine workers in surviving underground disasters. Several 
papers address the performance of present self-contained self-rescuers 
(SCSR's) and provide proposed guidelines for the design and testing of a 
second-generation SCSR. Improvements in the safety and effectiveness of 
mine rescue and recovery operations are described, including the design 
of a low-profile rescue breathing apparatus and a rescue team helmet. 



INTRODUCTION 



The Bureau of Mines life support re- 
search program is directed toward re- 
search into and development of breathing 
apparatus technology that increases the 
chances of miners surviving or being res- 
cued after an underground mine disaster. 
When a mine disaster occurs, the basic 
survival technique for a miner is to es- 
cape from the mine. Following a mine 
fire or explosion, the atmosphere inside 
the mine sometimes becomes oxygen defi- 
cient or filled with toxic gases. Under 
these circumstances, escape is nearly im- 
possible unless a miner is equipped with 
a self-rescue device that supplies oxygen 
without the need for breathing mine air. 
Federal regulations (30 CFR 75.1714) re- 
quire that every person who goes into 
an underground coal mine in the United 
States must be supplied with a self-con- 
tained self -rescuer (SCSR), a device 
capable of providing at least 1 h of oxy- 
gen regardless of ambient atmosphere. 
Only SCSR's approved by the National In- 
stitute for Occupational Safety and 
Health (NIOSH) and the Mine Safety and 
Health Administration (MSHA) can meet the 
provisions of the regulations. All of 
the 1-h-duration SCSR's are much larger 
and heavier than the conventional filter 
self -rescuer (FSR) which a miner wears on 
his or her belt as personal protective 
equipment. Unlike oxygen self -rescuers , 
FSR's protect only against low levels of 
carbon monoxide. Because of the size and 
weight of the 1-h SCSR's, in most cases 
the mining industry has elected to comply 
with the SCSR regulations by deploying 
the apparatus in a carry and store mode, 
which involves transporting the SCSR's 
into and out of the mine on a shift ba- 
sis. The carry and store mode allows the 
miner to store the SCSR within 5 min of 
the work site, provided that he or she 



continues to wear an FSR. The Bureau is 
conducting research to develop a second- 
generation, person-wearable SCSR (PWSCSR) 
that is approximately twice the size and 
weight of an FSR. A PWSCSR meeting these 
requirements could be worn on a miner's 
body, making it immediately available in 
the event of an emergency. 

A mine disaster may also result in the 
entrapment of miners whose normal egress 
from the mine is cut off. This often ne- 
cessitates a rescue operation by a spe- 
cially trained and equipped mine rescue 
team sent into the mine from the surface. 
Other Federal regulations (30 CFR 49) 
specify that mine rescue teams must be 
provided with rescue breathing apparatus 
(RBA's) that have at least 2-h service 
time and are approved for in-mine use. 
The Bureau of Mines is pursuing the de- 
velopment of smaller, lighter weight 
RBA's appropriately designed for use in 
the postdisaster environment, especially 
for low-coal rescue and recovery mis- 
sions. Another related technology in- 
volves the development of a rescue team 
helmet designed to integrate full head 
and eye protection with communication, 
illumination, and life support functions. 

The papers presented in these proceed- 
ings address some of the recent research 
conducted by the Bureau of Mines that has 
been directed toward the life support 
problems outlined above. The topics cov- 
ered range from basic research on the 
respiratory physiology of mine escape to 
new SCSR training programs. Any ques- 
tions or comments pertaining to this re- 
search are encouraged and appreciated. 

Throughout the proceedings, mention of 
trade names is made to facilitate under- 
standing; this mention does not imply 
endorsement by the Bureau of Mines. 



OVERVIEW OF LIFE SUPPORT ESCAPE BREATHING APPARATUS TECHNOLOGY 
By John G. Kovac 1 and Nicholas Kyriazi 2 



ABSTRACT 



This paper provides an overview of life 
support technology available today that 
is designed to meet the requirements 
of emergency escape following a mine 



disaster. The basic kinds of escape 
breathing apparatus are described, and 
U.S. and foreign experience with this 
technology is examined. 



INTRODUCTION 



When a mine disaster occurs, the basic 
survival technique for a miner is to es- 
cape from the mine. Following a mine 
fire or explosion, the atmosphere inside 
a mine may become oxygen deficient or 
filled with toxic gases. Under these 
circumstances, escape is impossible un- 
less a miner is equipped with a self-con- 
tained breathing apparatus. 

The purpose of this paper is to review 
the respirator technology available today 
to meet the requirements of emergency es- 
cape following a mine disaster. 

This paper is organized into three sec- 
tions. The first section defines the 
self-contained self-rescuer (SCSR). The 
next section describes the basic kinds of 
SCSR technology. Both U.S. and foreign 
experience with SCSR technology are exam- 
ined in the third section. 

DEFINITION OF SCSR 

Federal regulations (30 CFR 75.1714) 
require that every person who goes into 
an underground coal mine in the United 
States be supplied with an SCSR. An SCSR 
is an emergency breathing apparatus de- 
signed for the purpose of mine escape. 
It must be capable of providing at least 
a 60-min supply of oxygen (O2). Only 
SCSR's approved by the Mine Safety and 
Health Administration (MSHA) and the Na- 
tional Institute for Occupational Safety 
and Health (NIOSH) meet the provisions of 
these regulations. 

^Supervisory mechanical engineer. 
^Biomedical engineer. 
Pittsburgh Research Center, Bureau of 
Mines, Pittsburgh, PA. 



Other nations, including the Federal 
Republic of Germany and the U.S.S.R., 
have developed self-contained breathing 
apparatus designed for mine escape. Al- 
though some of these apparatus are not 
approved for use in the United States be- 
cause they do not satisfy performance or 
duration requirements contained in Fed- 
eral regulations for testing and certi- 
fication of respirators (30 CFR 11), all 
of these devices will be referred to as 
SCSR's. 

DESCRIPTION OF BASIC TECHNOLOGY 

All of the apparatus described in this 
report are one of two types: chemical- 
oxygen or compressed-oxygen. Most of the 
chemical-oxygen apparatus use potassium 
superoxide (KO2), a solid chemical, for 
both the oxygen source and the carbon 
dioxide (CO2) absorbent. One of the 
chemical-oxygen apparatus uses a sodium 
chlorate (NaC103) candle for an oxygen 
source and a separate chemical bed for 
CO2 absorption. An engineering drawing 
of a generic chemical-oxygen SCSR is 
shown in figure 1. 



Mouthpiece 

-Breathing hose 




Check valves 



Relief valve' 
FIGURE 1.— Chemical oxygen SCSR schematic. 




The compressed-oxygen apparatus use 
bottled oxygen under high pressure for 
the oxygen source with a separate chemi- 
cal bed, either lithium hydroxide (LiOH) 
or soda lime, both solid chemicals, for 
C0 2 absorption. An engineering drawing 
of a generic compressed-oxygen SCSR is 
shown in figure 2. 

U.S. AND FOREIGN EXPERIENCE 

Worldwide experience in SCSR technology 
can be broken down into three categories: 
SCSR's approved by MSHA and NIOSH, Bureau 
of Mines-developed prototypes, and for- 
eign apparatus. All of the apparatus are 
listed in table 1, with their rated ser- 
vice lives, country of origin, oxygen 
source, and size and weight. The sizes 
and weights of the different appara- 
tus are also shown in bar chart form in 
figures 3 and 4. The PASS and the MSA 
10/60 are not shown, the PASS because, it 
is unusual and unrepresentative and the 
10/60 because it has two parts. 



Mouthpiece 

'Breathing hose 





Check valves 



Cing bag ) 
Aij ) 

Relief valve"^ 




Demand 
Pressure ^ valve 
reducer and 
regulator 



Pressure gauge 
FIGURE 2.— Compressed oxygen SCSR schematic 



MSHA-NIOSH-Approved SCSR's 

CSE AU-9A1 

The AU-9A1 (figs. 5-6) is a compressed- 
oxygen self-rescuer with a throwaway 
steel bottle but otherwise reusable 
parts. It is field serviceable by 
trained personnel only. It has a 



TABLE 1. - Oxygen self -rescuers tested 



Apparatus 



Rated 

duration. 

min 



Country 



O2 source 



Weight, lb 



In use 



In case 



Volume, 
in 3 ' 



NIOSH-APPROVED 



CSE AU-9A1 

Draeger OXY-SR 60B 
MSA 60-min SCSR... 
Ocenco EBA 6.5.... 

PASS 700 

U.S.D. SCEBA-60... 



60 
60 
60 
60 
60 
60 



United States 
Germany (FRG) 
United States 

• • •uO» • ••••• • 

...do 



.do. 



Cylinder. 

K0 2 

K0 2 . 

Cylinder. 
...do 



,do. 



9.48 
7.49 
6.61 
6.83 
14.55 
7.14 



10.91 
8.38 
8.91 
7.74 

18.96 
7.56 



384 
459 
506 
528 
2,439 
453 







BUREAU PROTOTYPES 










60 
10 
70 
60 


United States 

...QO. ....... 


K0 2 


4.41 

1.81 

10.43 

3.85 


4.65 

2.73 

NA 

7.58 


210 


MSA 10-min PBA 1 . . . 


K0 2 


144 


Westinghouse PBA.. 


K0 2 


NA 


NaC10 3 candle 


459 



FOREIGN— NOT NIOSH-APPROVED 



Auer SSR-90 

AZG-40 

Draeger OXY-SR 30. 
Draeger OXY-SR 45. 
Fenzy Spiral II... 
WC-7 



90 
40 

30 
45 
45 
45 



Germany (FRG) 

China 

Germany (FRG) 
...do 



France 

U*o*o»£\.« • • •• • 



K0 2 

K0 2 , 

Cylinder. 
...do 



K0 2 , 
K0 2< 



6.79 
3.70 
5.27 
5.27 
6.72 
5.62 



10.34 
4.48 
5.27 
5.27 
7.69 
6.48 



310 
253 
369 
369 
400 
196 



NA Not available. 



NIOSH-approved prototype. 



Westinghouse PBA 

MSA 10-min PBA 

Lockheed PBA 

WC-7 

Fenzy Spiral II 

Draeger OXY-SR 45 

Draeger OXY-SR 30 

AZG40 

Auer SSR 90 

U.S.D. SCEBA-60 

Ocenco EBA 6.5 

MSA 60-min SCSR 

Draeger OXY-SR 60B 

CSE AU-9A1 




KEY 
^ NIOSH-MSHA-approved 
CSS Foreign; not NIOSH-approved 
■I Bureau prototypes 




100 



200 300 400 

VOLUME OF SCSR'S, cu in 



500 



600 



FIGURE 3.— Size comparison bar chart. 




4 5 6 7 

WEIGHT OF SCSR'S, lb 
FIGURE 4.— Weight comparison bar chart. 



bidirectional flow path, a constant O2 
flow of at least 1.5 L/min, and a pres- 
sure-activated demand valve and relief 
valve. The cylinder contains 130 L 2 , 
and the CO2 absorbent is LiOH. 

Draeger OXY-SR 60B 

The OXY-SR 60B (figs. 7-8) is a chem- 
ical-oxygen self-rescuer which can be 
returned to the distributor, National 
Mine Service, for refurbishing. It has 
a unidirectional flow path through the 
KO2 bed and a pressure-activated relief 
valve. A chlorate candle is provided for 
an initial spurt of oxygen until the K0 2 
bed is sufficiently activated by the 
user's breath. The K0 2 is pelletized. 

MSA 60-Min SCSR 

The MSA SCSR (figs. 9-10) is a chem- 
ical-oxygen self-rescuer that is entirely 
throwaway. It has a unidirectional flow 
path through the KO2 bed and a volume- 
activated relief valve. A chlorate can- 
dle is utilized for initial oxygen flow. 
The KO2 is in granular form. 

Ocenco EBA 6.5 

The EBA 6.5 (figs. 11-12) is a com- 
pressed-oxygen self-rescuer with a fiber- 
glass-wrapped, reusable aluminum bottle. 
The apparatus is ref urbishable only by 
the manufacturer. It has a unidirec- 
tional flow path with directional check 
valves in the mouth bit assembly, a con- 
stant flow of at least 1.5 L/min, and 
pressure-activated demand and relief 
valves. The cylinder contains 157 L O2, 
and the CO2 absorbent is LiOH. 

PASS 700 



pressure-activated relief valve. The 
cylinder contains 240 L O2, and the CO 2 
absorbent is soda lime. This apparatus 
is no longer being produced. 

U.S.D. SCEBA-60 

The SCEBA-60 (figs. 15-16) is a com- 
pressed-oxygen system that has some re- 
usable parts; it is not presently being 
commercially produced because it became 
available only after mine operators were 
required to have placed orders for their 
oxygen self -rescuers. It has a bidirec- 
tional flow path, a constant flow rate of 
oxygen of at least 1.5 L/min, and volume- 
activated demand and relief valves. The 
relief valve is triggered by bag volume 
but dumps from the breathing hose air 
that has not yet been scrubbed of CO 2 or 
enriched with oxygen. The device is 
available with a standard steel, throw- 
away bottle or a lightweight, fiberglass- 
wrapped aluminum, reusable bottle con- 
taining 130 L O2. The CO2 absorbent is 
LiOH. 

Bureau of Mines-Developed Prototypes 

Lockheed PBA (Personal 
Breathing Apparatus) 

The Lockheed PBA (figs. 17-18) is a 
NIOSH-approved prototype. The apparatus 
were manufactured in 1974 and stored in 
warehouses until tested for this study. 
These chemical-oxygen self-rescuers were 
intended to be throwaway devices. The 
flow path is unidirectional with check 
valves in the mouth bit. It has a pres- 
sure-activated relief valve and a chlo- 
rate candle for initial oxygen flow. 

MSA 10-Min PBA 



The PASS (Portable Air Supply Systems) 
self-rescuer (figs. 13-14) is a com- 
pressed-oxygen system with an aluminum 
bottle which is reusable after refur- 
bishing by the manufacturer. It has a 
unidirectional flow path through the 
CO2 scrubber, an enclosed breathing bag, 
no demand valve, a constant flow of 
oxygen of at least 3 L/min, and a 



These NIOSH-approved prototypes (figs. 
19-20) were also manufactured in 1974 and 
were similarly stored in warehouses until 
being tested. The 10-min PBA is a one- 
use, chemical-oxygen self -rescuer with 
bidirectional flow, a chlorate candle, 
and two breathing bags, one of which con- 
tains a volume-activated relief valve. 



MSA 10/60 Oxygen Self -Rescuer 

These NIOSH-approved prototypes (figs. 
21-22) were built in 1979 and were stored 
until being tested. The chemical-oxygen 
10/60 was designed so that the 10-min ap- 
paratus could be belt-worn with the 60- 
min canister being stored. In an emer- 
gency, the 10-min device is donned and 
the user proceeds to the storage place of 
the 60-min canisters, which are then at- 
tached without the need to remove the 
mouth bit. The oxygen source in both 
portions is KO2 . Chlorate candles are 
provided on both portions of the device; 
the candle on the 60-min portion is auto- 
matically activated when the device is 
attached to the 10-min portion. The en- 
tire apparatus is one-use only. The 10- 
min apparatus has a bidirectional flow 
path, but when the 60-min canister is at- 
tached, the flow path is changed to uni- 
directional flow. Figure 21 shows the 
10-min apparatus in the case and de- 
ployed, and the 60-min canister. The 60- 
min canister does not have its own case 
but is stored in a plastic bag. Figure 
22 is a schematic of the combined appara- 
tus, showing the flow scheme. 

Westinghouse PBA 

The Westinghouse PBA (figs. 23-24) is 
the first Bureau prototype ever devel- 
oped. The apparatus tested were manufac- 
tured in 1971 and were not certified by 
NIOSH. The flow path is bidirectional 
with a two-chambered breathing bag, one 
chamber for exhalation and one for inha- 
lation, with a pressure-activated relief 
valve on the inhalation side of the bag. 
The oxygen source is a large, L-shaped, 
NaC103 candle which provides at least 3 
L/min of O2 flow continuously, regardless 
of usage rate. The CO2 scrubber uses 
LiOH. The original directive for this 
contract included face protection, and 
the design included a combination hood- 
lens -noseclip-mouth-bit. Only three of 
these prototypes remained for testing in 
this study. 



Foreign Apparatus 

Auer SSR-90 

The SSR-90 (figs. 25-26), manufactured 
in the Federal Republic of Germany (FRG) 
by Auer, a subsidiary of MSA, is a chem- 
ical-oxygen self -rescuer which can be 
user-reburbished. It has a unidirec- 
tional flow path through the KO2 bed, a 
volume-activated relief valve, and a 
"quick starter" for initial oxygen flow. 

AZG-40 

The Chinese AZG-40 self -rescuer (figs. 
27-28) uses KO2 and is not reusable. It 
has a bidirectional flow path, a volume- 
activated relief valve which vents from 
the breathing hose, a heat exchanger, and 
a quick-starting mechanism for initial 
oxygen flow. 

Draeger OXY-SR 30 

The West German OXY-SR 30 (figs. 29-30) 
is a compressed-oxygen self -rescuer which 
is user reburbishable. It has a uni- 
directional flow path through the soda 
lime scrubber, a pressure-activated re- 
lief valve, a volume-activated demand 
valve, and a constant flow of oxygen of 
at least 1.5 L/min. The steel cylinder 
contains 64.5 L 02* 

Draeger OXY-SR 45 

The OXY-SR 45 (fig. 31) is nearly iden- 
tical to the OXY-SR 30 with two differ- 
ences: The constant flow rate is only 
1.2 L/min, and the oxygen flow cannot be 
turned off once it is activated. 

Fenzy Spiral II 

The French Spiral II (figs. 32-33) is 
a chemical-oxygen self -rescuer which is 
user serviceable. It has a unidirec- 
tional flow path through the KO2 bed and 
a pressure-activated relief valve. A 
very small compressed-oxygen bottle is 



utilized for initial startup. The bottle 
is yanked upward by pulling on a plastic 
ball connected to the bottle; this breaks 
a metal seal, rapidly releasing the con- 
tents into the system. 

WC-7 

The Soviet WC-7 self-rescuer (figs. 34- 
35) uses K0 2 as the oxygen source and is 
throwaway. It has a bidirectional flow 
path device with a volume-activated re- 
lief valve. The starting device utilized 
delivers 6 L 2 within 30 s. 

PERFORMANCE COMPARISON 

A performance study of oxygen self- 
rescuers from the United States and other 
countries was undertaken as an assessment 



of present worldwide technology. The ap- 
paratus were tested on a breathing and 
metabolic simulator in the life support 
laboratories of the Bureau of Mines. 
Parameters monitored during the testing 
were inhaled levels of C0 2 and 2 , in- 
haled gas temperature, and breathing re- 
sistance. The metabolic demand placed on 
the apparatus represented the average 
demand of the 50th-percentile miner per- 
forming a 60-min Man-Test 4, as described 
in 30 CFR 11H. 

Results presented in tables 2 and 3 in- 
clude apparatus duration, reasons for 
terminating a test, and averages and 
peaks of monitored parameters. Figures 
36 and 37 are the comparison curves of 
weight versus capacity and volume versus 
capacity, respectively, for SCSR's that 
are, or could have been, deployed in 



TABLE 2. - Means of average values of monitored parameters 
(Standard deviations in parentheses) 



Apparatus 



Dura- 
tion, 
min 



Cause of 
termination 



2 , pet 



C0 2 , pet 



Resistance, 
mm H2O 



Exha- 
lation 



Inha- 
lation 



Temper- 
ature, 
°C 



CSE AU-9A1 

Draeger OXY-SR 

60B. 
MSA 60-min SCSR. . 

Ocenco EBA 6.5. . . 
PASS 700 

U.S.D. SCEBA-60. . 

Lockheed PBA 

MSA 10-min PBA... 
MSA 10/60: 

10-min 

60-min 

Westinghpouse PBA 

Auer SSR-90 

AZG-40 

Draeger OXY-SR 30 
Draeger OXY-SR 45 

Fenzy Spiral II. . 
WC-7 



73 (6) 

72 (4) 

83 (6) 

110 (8) 

86 (7) 

79 (10) 

34 (9) 

14 (1) 

9 (1) 

73 (21) 
60 (1) 
82 (2) 
38 (3) 
47 (4) 
55 (7) 

34 (3) 

67 (4) 



High C0 2 

Low bag volume 

Low bag volume 

or high C0 2 . 
Low bag volume 

• • • & O • • •• ••• •• 

Low bag volume 
or high C0 2 . 

High CO 2 , low 
bag volume, 
or low 2 . 

High C0 2 

High C0 2 

Low bag volume 

• • • CO • •••••••• 

Low bag volume 

High C0 2 

Low bag volume 
Low bag volume 

or high C0 2 . 
Low bag volume 
High C0 2 or 

low bag 

volume. 



70 
78 



(13) 
(3) 



2.5 
1.0 



(0.1) 
(.1) 



82 (1) 

74 (7) 
81 (3) 
71 (10) 

60 (16) 



44 (4) 



1.0 (.2) 



.7 
1.1 
2.2 



(.2) 
(.1) 
(.4) 



1.6 (.5) 



1.8 (.2) 



50 (8) 
46 (6) 

58 (6) 

51 (5) 
51 (4) 
54 (7) 

113 (30) 



63 (8) 



50 (4) 

26 (6) 

26 (3) 

38 (3) 

24 (3) 

56 (2) 

120 (46) 



119 (5) 



42 
37 



(1) 
(2) 



44 (2) 



41 
39 
40 



(1) 
(1) 
(1) 



49 (10) 



47 (3) 



37 
67 
84 
81 
66 
80 
76 



(10) 
(ID 
(1) 
(5) 
(5) 
(3) 
(7) 



64 (4) 
77 (4) 



1.6 
2.2 
.6 
.7 
2.5 
1.5 
1.6 

1.7 
1.8 



(.1) 
(.6) 
(.1) 
(.1) 
(.1) 
(.2) 
(.1) 

(.7) 
(.1) 



74 
83 

121 
57 

116 
45 
42 



(10) 
(13) 
(35) 
(5) 
(9) 
(3) 
(9) 



56 (12) 
63 (5) 



79 
60 
31 
35 
101 
19 
18 

22 
59 



(12) 
(15) 
(6) 
(3) 
(9) 
(2) 
(1) 

(7) 
(5) 



38 
42 
40 
40 
50 
41 
41 



(2) 
(2) 
(2) 
(2) 
(4) 
(0) 
(1) 



36 (2) 
56 (4) 



TABLE 3. - Means of peak values of monitored parameters 
(Standard deviations in parentheses) 



Apparatus 



°2> pet 



C0 2 , pet 



Resistance, mm H2O 



Exhalation 



Inhalation 



Tempera- 
ture, °C 



CSE AU-9A1 

Draeger OXY-SR 60B 
MSA 60-min SCSR. .. 
Ocenco EBA 6.5. .. . 

PASS 700 

U.S.D. SCEBA-60. .. 

Lockheed PBA 

MSA 10-min PBA 

MSA 10/60: 

10-min 

60-min 

Westinghouse PBA.. 

Auer SSR-90 

AZG-40 

Draeger OXY-SR 30. 
Draeger OXY-SR 45. 
Fenzy Spiral II... 
WC-7 



76 
93 
91 
81 
89 
79 
75 
57 

44 
76 
91 
88 
79 
82 
81 
89 
85 



(10) 
(2) 
(2) 

(12) 
(4) 
(6) 

(13) 
(5) 

(10) 
(12) 
(1) 
(4) 
(2) 
(3) 
(8) 
(1) 
(5) 



4.0 (0) 
1.3 (0.1) 

3.1 (1.2) 
(.5) 
(.4) 
(.8) 

(1.0) 
(0) 



1.8 
1.5 
2.9 
3.4 
4.0 



4.0 
3.0 
.9 
1.7 
4.0 
2.0 
2.8 
2.0 
3.8 



(0) 
(.8) 
(.2) 
(.3) 

(0) 
(.4) 
(.9) 
(.7) 
(.4) 



56 
83 
69 
54 
53 
59 
148 
82 

114 

117 

136 

66 

160 

52 

48 

80 

75 



(9) 

(18) 

(13) 

(5) 

(3) 

(7) 

(34) 

(15) 

(15) 
(40) 
(35) 

(7) 
(10) 

(4) 

(7) 
(29) 

(9) 



55 

45 
40 
41 
27 
65 
157 
221 

137 
80 
61 
48 

153 
21 
21 
42 
78 



(6) 

(19) 

(14) 

(1) 

(3) 

(7) 

(48) 

(13) 

(31) 

(47) 

(13) 

(4) 

(9) 

(2) 

(3) 

(19) 

(12) 



44 
44 
53 
43 
42 
42 
64 
53 



(2) 
(3) 
(1) 
(1) 
(1) 
(1) 
(16) 
(3) 



45 (2) 

47 (3) 
44 (2) 

48 (2) 
60 (6) 
44 (1) 
44 (1) 
43 (2) 
69 (5) 



large numbers in underground mines. Both 
curves were generated by using standard 
linear regression analysis on SCSR per- 
formance comparison data. Because the 
SCSR's were tested at a constant oxygen 



consumption rate, capacity is defined as 
the product of oxygen consumption rate 
and duration. Capacity measures the 
amount of oxygen an SCSR can provide for 
escape purposes. 



CONCLUSIONS 



The comparison curves illustrate three 
important points: (1) Size and weight 
of SCSR's can be reduced by decreasing 
the oxygen capacity; (2) more efficient 
designs in terms of size and weight uti- 
lization are possible using current tech- 
nology; (3) at an average oxygen con- 
sumption rate of 1.35 L/min, an 81-L 



apparatus would have a duration of 60 
min. Reducing the oxygen capacity to 81 
L would result in an SCSR at least 20% 
smaller than current apparatus, thus 
opening up the possibility of developing 
second-generation SCSR's, which could be 
worn by a miner as personal equipment. 



10 





FIGURE 5.— CSE AU-9A1 in case and deployed. 



Demand valve 



2 

pressure gauge 



2 
cylinder 



Breathing 
bag 



Nose 
clip 



Pressure-reducing 
valve 

Relief valve 

Relief valve 
chamber 

Bypass 
hose 




KEY 
i=zz> Inhale 
■■► Exhale 
i=r>0 Oxygen 



FIGURE 6.— CSE AU-9A1 schematic. 



11 




FIGURE 7.— Draeger OXY-SR 60B in case and deployed. 



Mouthpiece 
Corrugated hose 



Inhalation valve disks 
Exhalation valve 




Plug , mouthpiece 



Upper valve chamber 
Heat exchanger 



Breathing bag 
Hose clamp 



K0 2 bed 



KEY 
C=£> Inhale 
^■^ Exhale 



FIGURE 8.— Draeger OXY-SR 60B schematic. 



12 




FIGURE 9.— MSA 60-Min SCSR in case and deployed. 



Breathing hose 



Mouthpiece 



Breathing bag 




Breathing bag 



KEY 
C=£> Inhale 
^■^ Exhale 



Detail "A" 

FIGURE 10.— MSA 60-MIN SCSR schematic. 



13 




FIGURE 11.— Ocenco EBA 6.5 in case and deployed. 



Goggles 



Nose clip 



Breathing 
bag 



Relief 
valve 



KEY 
i > Inhale 
— "^ Exhale 
c=£C> Oxygen 



Neck 
harness 



Mouthpiece 
assembly with 
check valves 



Demand 
valve 




C0 2 -absorbent 
canister 



Waist 
harness 



FIGURE 12.— Ocenco EBA 6.5 schematic. 



14 




FIGURE 13.— PASS 700 in case and deployed. 



Mouthpiece 



Breathing 
hose 



Start valve 




KEY 
i > Inhale 
■■^ Exhale 
<=$£> Oxygen 



FIGURE 14.— PASS 700 schematic. 



15 




FIGURE 15.— USD SCEBA-60 in case and deployed. 



Mouthpiece and 
breathing hose 



Constant- flow regulator 
and demand — -^^,- 
valve inside bag .^f 




Outer case 



KEY 

> Inhale 

Exhale 

c=J>t> Oxygen 



FIGURE 16.— USD SCEBA-60 schematic. 



16 





FIGURE 17.— Lockheed PBA in case and deployed. 



Mouthpiece with 
check valves 



N aC 1 3 candle 




KO2 catcher 



Baffles 



Nose clip 



Hoses 



m ^— Return duct 



Filters 



KEY 
:> Inhale 

+ Exhale 



Relief valve 



Breathing bag 



FIGURE 18.— Lockheed PBA schematic. 



17 




FIGURE 19.— MSA 10-Min PBA in case and deployed. 



Breathing bag 



Relief valve 



Filtered K0 2 bed 



Mouthpiece 




Heat exchanger 



KEY 
<=> Inhale 

■"■+- Exhale 



NaCI0 3 candle 



Breathing bag 



FIGURE 20.— MSA 10-Min PBA schematic. 



18 




FIGURE 21.— MSA 10/60 oxygen self-rescuer in case and deployed, and 60-min canister. 




»» Inhalation 

Exhalation 



FIGURE 22.— MSA 10/60 oxygen self-rescuer schematic. 




19 



0^ 



„#' 



** 



»*•'■■ 





FIGURE 23.— Westinghouse PBA in case and deployed. 



Inhalation 
check valve 



Inhalation hose 




Exhalation 
check valve 



Exhalation hose 



KEY 

i > Inhale 

^^^ Exhale 
<=» Oxygen 



FIGURE 24.— Westinghouse PBA schematic. 



20 




FIGURE 25.— Auer SSR-90 in case and deployed. 



Cover 



Breathing hose 
with mouthpiece 



Heat exchanger 
Breathing bag 

Check-valve housing 
Particle filter 



Heat protection 
K0 2 bed 



Bottom part 
of container 




Locking device 



Safety goggles 

Nose clip 

Relief valve 
Neck strap 



Corrugated hose 

Breathing bag 
connector 



Waist strap 



NaCIO, candle pull pin 



Carrying strap 



FIGURE 26.— Auer SSR-90 schematic. 



21 




FIGURE 27.— AZG-40 in case and deployed. 



Mouthpiece 



Relief valve Valve _/_ 

(see detail) 



Rubber casing 



Heat exchanger 



Nose clip 




Breathing 
bag 




K0 2 canister 



FIGURE 28.— AZG-40 schematic. 



22 







FIGURE 29.— Draeger OXY-SR 30 in case and deployed. 



Nose clip 



Breathing hose 
with mouthpiece 



Breathing bag 



Constant-flow regulator 
Demand valve 




Nose clip 



Pressure gauge 



Relief valve 
Check valve 

Valve chamber 

C0 2 absorbent 
Central pipe 



-Collecting chamber 
FIGURE 30.— Draeger OXY-SR 30 schematic. 



Breathing hose 
with mouthpiece 



Breathing bag 



Constant- flow regulator 
Demand valve 




Relief valve 
Check valve 

Valve chamber 

C0 2 absorbent 
Central pipe 



-Collecting chamber 
FIGURE 31.— Draeger OXY-SR 45 schematic. 



23 




FIGURE 32.— Fenzy Spiral II in case and deployed. 



Mouthpiece 



Relief valve 




Full-depth plenum 



FIGURE 33.— Fenzy Spiral II schematic. 



24 





'-> 




FIGURE 34.— WC-7 in case and deployed. 



Mouthpiece 



Breathing hose 



NaCI0 3 candle 



KEY 
Inhale 
Exhale 




Nose clip 



Relief valve 



Breathing bag 



Outer case 



FIGURE 35.— WC-7 schematic. 



o 



10 



=9 6 



4 - 



25 



.-* ■ 



50 



100 



150 



2 CAPACITY, L 



FIGURE 36.— Weight versus capacity comparison curve of self-contained self-rescuers 
generated from data compiled by the Bureau of Mines. 



600 r 



500 



400 



3 
O 



O 300 

> 



200 



100 



/■ 



50 



100 



150 



2 CAPACITY, L 



FIGURE 37.— Volume versus capacity comparison curve of self-contained self-rescuers 
generated from data compiled by the Bureau of Mines. 



26 



PROBLEMS IN DONNING SELF-CONTAINED SELF-RESCUERS 
By Charles Vaught 1 and Henry P. Cole 2 



ABSTRACT 



In 1986 University of Kentucky and Bu- 
reau of Mines researchers participated in 
a series of related SCSR donning studies. 
To establish a baseline for their inves- 
tigations, they interviewed more than 50 
mine safety instructors, rescue team mem- 
bers, and inspectors. The interviews 
support a widely held notion that very 
few underground coal miners ever actually 
don an SCSR in training. Rather, the 
typical training session will include a 
film, a slide-tape presentation, or a 
talk by an instructor who stands before 
the class and demonstrates the steps 
involved. 

Given the industry's heavy reliance on 
abstract training methods, the research 
staff reviewed all generally available 
literature for the four models in common 
use (CSE, Draeger, MSA, and Ocenco). 



They targeted three main concerns with 
current training materials: (1) The rec- 
ommended donning position appears diffi- 
cult and inefficient and is impossible 
for miners working in low coal, (2) the 
donning sequence tends to place nones- 
sential and time-consuming tasks such 
as strap adjustment ahead of some of the 
steps necessary to isolate one's lungs 
from the surrounding atmosphere, and 
(3) the materials present no simplified, 
easy-to-remember procedural rules to help 
miners order the complex array of tasks 
needed to use the device in an emergency. 
An innovative training package was 
developed and field-tested. The data in- 
dicate that the new approach has great 
promise for improved SCSR donning 
efficiency. 



INTRODUCTION 



During 1986 researchers and technical 
staff from the University of Kentucky, 
the Bureau of Mines, the Mine Safety and 
Health Administration, the Kentucky De- 
partment of Mines and Minerals, and two 
coal companies conducted a series of re- 
lated SCSR donning studies. Prior to 
this research there had been little sys- 
tematic investigation of miners' ability 
to put the devices into use, although 
there had been many evaluations of SCSR 
durability, reliability, and duration of 
oxygen supply under various levels of 
physical exertion. 

One exception found in the literature 
is the report of a field evaluation of 
the Draeger OXY-SR 60B and the MSA Model 
464213. 3 Donning times for 46 miners 
were recorded and shown to range from 30 

'Research sociologist, Pittsburgh Re- 
search Center, Bureau of Mines, Pitts- 
burgh, PA. 

^Educational pychologist, University of 
Kentucky, Lexington, KY. 



to 192 s. The average time for all sub- 
jects was 90 s. This report, although 
informative, does not indicate the fre- 
quency and types of donning errors, times 
for completion of part tasks, or whether 
the individuals were given assistance 
during their performance trials. 

INITIAL AREAS OF CONCERN 

To establish a baseline for the pres- 
ent studies, project researchers reviewed 
all available training materials dealing 
with the care and donning of the four 
SCSR models in common use (CSE, Draeger, 

^Peluso, R. G. Results from the Field 
Evaluation of Self-Contained Self-Res- 
cuers. Paper in Proceedings of the 12th 
Annual Institute on Coal Mining Safety 
and Research, ed. by M. Karmis, M. H. 
Suthrland, J. L. Patrick, and J. R. Lu- 
cas. VA Polytech. Inst, and State Univ., 
Dep. Min. and Miner. Eng. , Blacksburg, 
VA, 1981, pp. 125-131. 



27 



Ocenco, and MSA). They also interviewed 
more than 50 mine safety instructors, 
rescue team members, and inspectors. 
These individuals were asked to describe 
the performance capabilities of under- 
ground coal miners in using the devices. 
The preliminary inquiries suggested sev- 
eral actual or potential problem areas 
both in approaches to training and in ac- 
tual performance. The most significant 
of these are discussed in the following 
sections. 

Logical Problems With Existing 
Training Materials 

The research staff targeted three main 
concerns with current training materials 
for donning SCSR's. First, the recom- 
mended donning position appears difficult 
and inefficient. It is impossible for 
miners working in low coal. Second, the 
donning sequence tends to place nonessen- 
tial and time-consuming tasks such as 
strap adjustment ahead of some of the 
steps necessary to isolate one's lungs 
from the ambient atmosphere. Third, the 
materials present no simplified, easy-to- 
remember procedural rules that will help 
miners order the complex array of tasks 
needed to use the device in an emergency. 

Generally, the available materials show 
an individual donning the SCSR while 
standing in a well-lighted room. The 
demonstrator first inspects the seals and 
pressure gauge and then performs those 
tasks necessary to allow him to work with 
the device while standing. Only then 
does he or she complete the steps needed 
to isolate the lungs from the surrounding 
atmosphere; the final critical task (put- 
ting on the nose clips, for instance) may 
be slotted as late as 10th in a sequence 
of 14 or more steps. Furthermore, in the 
materials it is not clear what is to be 
done with the cap and cap lamp. Some 
illustrations depict the cap without a 
lamp. Some show the demonstrator hanging 
the lamp cord around the neck, letting 
the cap and lamp dangle down the side. 
Still others seem to indicate that the 
individual removes and replaces the cap 
as he or she does steps that require the 
cap to be off. 



In sum, these materials seem to advocate 
a training approach that is decidedly 
less than optimum for real-life condi- 
tions. An actual emergency might well 
entail a miner kneeling in a smoky entry 
in low coal where the only illumination 
would be that provided by his or her cap 
lamp. In such a predicament the SCSR 
would have to be donned quickly; it would 
have to be put on while working in an 
awkward position; and the lamp would 
need to be placed so that its beam could 
shine directly on the device. If one can 
imagine this situation, the value of a 
straightforward, easily remembered don- 
ning procedure and thorough hands-on 
training becomes readily apparent. 

Lack of Hands-on Training 

The interviews support a widely held 
notion that a majority of underground 
coal miners never actually don an SCSR. 
The typical training session will include 
a film, slide-tape presentation, or a 
talk by an instructor who stands before 
the training class and demonstrates the 
steps involved. Summary statistics for a 
series of mine trainer workshops con- 
ducted by Cole 4 revealed that the modal 
prior donning experience for individuals 
in most workshops was zero. This indi- 
cates there are a number of instructors 
teaching miners how to don the SCSR who 
have never themselves had one on. 

The widespread lack of hands-on exper- 
ience is a serious matter. There is a 
myriad of research to support the common- 
sense notion that lecture and demonstra- 
tion do not constitute an effective means 
of teaching motor tasks. In the inter- 
views, dollar costs were most frequently 
cited as the reason there is not more 
practice with the devices. The cost of 
using real SCSR's for the training of 
miners is approximately $400 to $600 per 
unit. Training models cost about the 
same. Thus, training facilities that 

4 See "Training in the Use of the Self- 
Contained Self-Rescuer," by H. P. Cole 
and C. Vaught, later in these 
proceedings. 



28 



have an SCSR for demonstration purposes 
rarely provide more than one. 

A second factor often mentioned by the 
interviewees is the time required to 
train each individual on the apparatus. 
The session itself, with corrective in- 
structions and practice, requires from 5 
to 10 min per person. Sanitizing the 
mouthpiece and repacking the SCSR for the 
next trainee is reported to take an addi- 
tional 5 to 10 min. With large groups of 
miners and limited time for training, 
these time requirements are seen as 
prohibitive. 

Observed Motor Performance Errors 

Six of the individuals interviewed had 
observed miners putting on one or more of 
four SCSR models and were able to provide 
impressionistic data about types of per- 
formance errors most commonly committed. 
In all cases reported, the units were 
being donned to carry out equipment re- 
liability and duration studies, or for 
training purposes. The informants were 
asked to list the kinds of errors they 
witnessed and to comment on the ability 
of miners to put the devices into 
operation. 

One mine safety instructor had recently 
carried out a hands-on exercise with the 
Ocenco EBA 6.5. The training was done 
with a total of 96 workers. These indi- 
viduals were divided into groups of ap- 
proximately 18 subjects. Each group was 
taken underground and given a 10-min dem- 
monstration of the function, care, and 
use of the unit. Immediately following 
the demonstration the miners were se- 
lected nine at a time and placed near an 
overcast. Each person was given an SCSR. 
At a signal from the trainer all nine be- 
gan to don the devices. The instructor 
observed and prompted the trainees during 
the process. 

This informant agreed to rank observed 
errors according to frequency, but cau- 
tioned that mistakes he noticed with the 
first subjects were pointed out to miners 
in later groups before they could make 
the error. The trainer summarized his 
impressions as follows: (1) Most of the 
miners had the SCSR's on in approximately 



1 min, but some required prompting for 
specific steps, (2) the most common error 
was failure to put on the nose clips — 
made by about one-fourth of the subjects, 
(3) approximately one person in each 
group of nine failed to put on the gog- 
gles, (4) slightly less than one person 
in each trial group had difficulty with 
the oxygen valve, (5) a few individuals 
put the neck strap over the lamp cord — 
this necessitated removing the SCSR and 
then the cap in order to put on the head 
strap, and (6) 2 out of the 96 had the 
bite lugs gripped in their incisors and 
the mouthpiece seal on the outside of the 
lips. 

The other informants who had witnessed 
miners putting on SCSR's were less sys- 
tematic in their recollections. However, 
they tended to agree that the most common 
problems were kinked air hoses, failure 
to put on nose clips, and omission of the 
goggles. It was also noted that trainees 
often did not follow the recommended se- 
quence when donning the equipment. 

None of these observations were based 
upon planned studies of performance. 
Therefore, little can be inferred about 
the optimal sequence of steps, the par- 
ticular parts of the task most prone to 
error, or the effect of training. Yet 
this type of information is useful in de- 
veloping a more systematic approach to 
donning the SCSR. It can reveal some- 
thing about the parts of the task that 
are retained well and those that are not 
so well retained. It can be useful in 
designing controlled human performance 
studies such as the one conducted during 
the present research. 

THE FIRST CONTROLLED DONNING ASSESSMENT 

A coal company in eastern Kentucky par- 
ticipated in the initial study and fur- 
nished working models of the SCSR (the 
CSE AU-9A1) in use at its mines. The 
company trainers assisted in the design 
of the experiment, which is shown in ta- 
ble 1. Performance was observed under 
three trial conditions: (1) The baseline 
group (N=14) had no previous hands-on 
training with an SCSR, had never parti- 
cipated in a demonstration of an SCSR, 



29 



and had not received written or oral 
instructions about the device; (2) the 
control group (N=20) had hands-on train- 
ing with the CSE 4 yr previously and 
at least one demonstration of the same 
model annually, the most recent having 
taken place 7 months prior to the study; 
(3) the treatment group (N=16) was iden- 
tical to the control group in terms of 
previous experience except that they col- 
lectively received a donning demonstra- 
tion immediately preceding their perfor- 
mance trial. 

The tasks were administered individ- 
ually in a specially arranged training 
room. Each person, wearing a miner's 
cap, belt, lamp, and filter self-rescuer 
(FSR), was brought into the room and 
asked to stand behind a line near the 
front wall. The SCSR was placed one 
case-length in front of the line with its 
bottom latch pointed toward the subject 
and the neck strap adjusted all the way 
out. The individual was given a standard 
set of instructions which stated the pur- 
pose of the study and requested him or 
her to put the SCSR on as if there were a 
fire. At a signal from the researchers 
the person began to don the unit. A 
video camera mounted on a tripod at the 
back of the room recorded the entire se- 
quence. When the individual was fin- 
ished, he or she took one step forward 
and raised the right arm. After the 
trial the person was shown the videotape, 
and all donning errors were corrected. 

The purpose of the study was to compare 
the SCSR donning performance of the three 
groups. Differences in donning speed, 
proficiency, and errors could be related 
to no training (baseline group) ; initial 
hands-on training and annual demon- 
strations (control group); and initial 

TABLE 1. - Treatment groups and 
conditions 



Group 


Base- 


Control 


Treat- 




line 




ment 




14 


20 


16 


Underground miner. . 


No 


Yes 


Yes 


Hands-on training. . 


No 


Yes 


Yes 


Demonstration: 








7 months prior... 


No 


Yes 


Yes 


Immediately prior 


No 


No 


Yes 



hands-on training, annual demonstrations, 
and a recent demonstration (treatment 
group). 

It was assumed that the treatment re- 
fresher given by the company trainer 
would be based on the manufacturer's rec- 
ommended sequence, as had all his earlier 
training. During the week in which the 
experiment was conducted, however, the 
trainer started to doubt the efficacy of 
the donning procedure he had been teach- 
ing. After consulting with a fellow in- 
structor, he began to develop a simpli- 
fied method designed to allow the miner 
to kneel and to isolate her or his lungs 
before completing secondary tasks. When 
It was time to give his demonstration to 
the treatment group, the trainer kneeled 
and performed the task using the new se- 
quence. The procedure was not presented 
to the miners either visually or orally, 
because at that time it had not been for- 
malized. This change in the training of 
the treatment group confounded the exper- 
iment. Observed differences in donning 
sequence, proficiency, and times could be 
caused both by recency of training and by 
change in approach. Nevertheless, much 
was learned from the study. Selected 
findings are discussed below. 

Completion of Critical Tasks 

There are three tasks that a miner must 
perform correctly in order to survive 
in a toxic atmosphere: (1) activate the 
oxygen, (2) insert the mouthpiece, and 
(3) put on the nose clips. This does 
not, of course, ensure that the SCSR is 
secured in a manner that will allow 
enough maneuverability for him or her to 
get out of a mine. Completion of the 
critical tasks should be regarded as an 
absolute minimum, therefore, not as a 
criterion for self-rescue and escape. 

The individuals in the experiments were 
allowed all the time they wanted to com- 
plete the donning trial. The performance 
was stopped only when a person signaled 
that he or she was finished. Generally, 
the subjects believed that they had been 
able to isolate their lungs from the sur- 
rounding atmosphere and were prepared to 
travel through heavy smoke. As table 2 



30 



indicates, however, a majority of people 
in all three groups would probably have 
perished in an actual mine fire or explo- 
sion. This might be expected with naive 
individuals such as those in the base- 
line group, but those in the control and 
treatment groups were atypical in that 
they, unlike most miners, had had hands- 
on SCSR training and systematic annual 
demonstrations. 

Inspection of table 2 shows that only 1 
of the 14 subjects in the untrained group 
would have had a chance of surviving and 
he required approximately 95 s to com- 
plete the three critical steps. An im- 
portant conclusion to be drawn from the 
performance of the baseline group is that 
the sequencing of steps necessary to don 
the apparatus proficiently is not well- 
cued by the equipment or by previously 
completed steps. Tasks that are not ade- 
quately cued are those most likely to be 
forgotten. -* 

Only 9 (56.25%) of the 16 miners in the 
treatment group were successful in doing 
the critical tasks. As can be seen in 
table 2, they tended to finish this part 
of the donning sequence more quickly than 

-Mlagman, J. D., and A. M. Rose. Reten- 
tion of Military Tasks: A Review. Human 
Factors, v. 25, No. 2, 1983, pp. 199- 
21 3. 

TABLE 2. - Number of persons completing 
the critical steps within specific 
time frames 



Time frame, s 



Base- 
line, 
14 



0-19 

20-39 

40-59 

60-79 

80-99 

100-119 

120-139 

140-159 

160-179 

180-199 

Total completing 



Group and number 
attempting 








1 









Control, 
20 



13 



Treat- 
ment, 
16 



those in the control group. The shorter 
times required by these individuals are 
related to two factors which cannot 
be unconfounded. First, miners in the 
treatment group received a refresher 
demonstration only 2 to 4 h prior to 
their trial. Some of the increased speed 
with which they performed is probably due 
to this experience. Second, however, the 
procedure was changed by the instructor. 
Treatment group members were shown a new 
position (kneeling) and a new donning 
method that had them attempt the critical 
steps early in the sequence. The more 
rapid completion of these tasks by this 
group is due primarily to the second 
factor. 

There is another element that has a 
bearing on the percentage of subjects in 
the treatment group who were able to com- 
plete the critical tasks. In the demon- 
stration they were instructed to open the 
case on the floor, do the critical steps, 
slip the neck strap under and around the 
unit, and then don it. As was mentioned 
previously, in the experiment the SCSR 
was placed with the bottom latch toward 
the subject. Eight (50%) of the miners 
in the treatment group opened the case 
from the wrong end and proceeded to per- 
form the critical tasks. When it was 
time to slip the neck strap under and put 
it on, they found they had the device 
turned backward. Several of them became 
confused and in trying to correct the er- 
ror omitted one or another of the criti- 
cal steps. 

Given all the time they needed, 13 
(65%) of the 20 individuals in the con- 
trol group were successful in isolating 
their lungs. If they had had to do so 
within 1 rain, however, only five (25%) 
would have survived. Members of this 
group were trained in the approved man- 
ner. In this procedure, adjusting the 
neck strap precedes and delays completion 
of the three critical tasks. Likewise, 
working in a standing position also makes 
it more difficult to open the case and 
complete the donning sequence. Many of 
the miners in the control group quickly 
gave up or did not attempt to don the 
head strap, adjust the neck strap, or tie 
the waist straps. Rather, a typical 



31 



response was to lift the SCSR up in one 
arm (usually crushing the breathing bag) 
and carry the unit with straps unadjusted 
and untied. Indeed, review of the video- 
tapes reveals that the individuals in the 
control group were even less prepared for 
escape than were those in the treatment 
group. 

Completion of Secondary Tasks 

Some idea of the effect of the recent 
demonstration on performance can be got- 
ten by inspecting table 3, which gives 
the percentage of each group completing 
each task. The miners in the treatment 
group were conscientious about attempting 
secondary tasks such as donning the head 
strap, putting on their goggles, adjust- 
ing the neck strap, and tying the waist 
straps. On average, the members of this 
group finished significantly more steps 
than those in the control group but spent 
no less time on the total trial (table 
4). All in all, however, it must be con- 
cluded that both groups of trained miners 
generally lacked proficiency. They often 
made errors and interrupted tasks. Both 
groups required relatively long times to 
complete the secondary donning steps, as 

TABLE 3. - Percent of each group 
completing each task 



TABLE 4. - Mean times and standard 
deviations for persons completing 
critical and secondary donning 
steps, seconds 





Group and number 
attempting 




Base- 
line, 
14 


Control, 
20 


Treat- 
ment, 
16 




100 
50 
86 

100 
36 
93 
21 
57 
64 
71 
71 
50 
7 



100 
95 
75 

100 
85 
95 
75 
80 
60 
65 

100 
65 
25 
20 


100 
88 


Air hose extended.. 
Mouth plug pulled. . 
Mouthpiece inserted 


88 
100 

88 
100 

69 

81 
100 


Breathing bag open. 


100 

100 

94 


Neck strap adjusted 
Waist strap tied... 


100 
100 





Control 
group 


Treat- 
ment 
group 


Critical steps: 


84.5 
44.8 

130.4 
73.4 

13 


44.9 


Standard deviation.... 
Secondary steps: 


14.6 
127.4 


Standard deviation.... 
Total persons completing 


45.9 
9 



table 4 indicates. Most importantly, a 
sizable number probably could not have 
escaped a fire or explosion. 

SUBSEQUENT DONNING ASSESSMENTS 

Insights gained from the first con- 
trolled assessment led the researchers to 
formalize a more logical donning position 
and a simplified procedure. Using this 
method, the miner in an emergency would 
take the SCSR from its storage box, 
kneel, and place the unit on the mine 
floor directly in front of his or her 
knees. He or she would then lay the hat 
on the mine floor so that the lamp could 
shine directly on the SCSR. After loop- 
ing the neck strap loosely over the head, 
the miner would bring his or her face 
close to the unit and work with both 
hands to complete the following "chunked" 
sequence of steps: (1) activate the oxy- 
gen, (2) insert the mouthpiece, and 
(3) put on the nose clip. Doing these 
three things on the front end would rap- 
idly isolate her or his lungs from a 
toxic mine atmosphere. The next tasks 
would be to (4) put on her or his gog- 
gles, (5) adjust both the neck and waist 
straps to place the SCSR close to chin 
and chest, and (6) replace the cap and 
move out. 

This new approach is a generalized se- 
quence which assumes the individual steps 
for implementing a particular model of 
SCSR have been demonstrated to and (ide- 
ally) practiced by miners in hands-on 



32 



training. What people forget is not how 
to do the discrete tasks. Rather, they 
tend to omit steps, or attempt them out 
of sequence. If miners were to be given 
a performance trial shortly after being 
trained in a 12- or 14-step donning pro- 
cedure, they could be expected to jump 
around from task to task, to begin but 
not complete a step before starting on 
another, and to forget some steps entire- 
ly. In fact, the experimental data from 
the first donning assessment showed this 
to occur frequently. 

It is much easier to remember to do 
tasks in their proper sequence if the en- 
tire process is placed in a simple, logi- 
cal framework that organizes them all. 
The approach developed in this research 
serves that purpose. If a miner can re- 
member the general steps given above, 
each one cues the recall of the tasks 
that are part of that step. addition, 
the simplified procedure helps the indi- 
vidual to order the overall sequence of 
donning tasks so that critical steps are 
done early and secondary ones later. 



This donning method has been field- 
tested with approximately 16 groups of 
coal industry people in 3 States. Each 
group was given an explanation of the new 
donning position and the simplified se- 
quence. The advantages of the procedure 
were explained, and then demonstrated by 
showing a 2-min videotape. The individ- 
uals next began actual donning trials. 
While one miner was putting an SCSR on, 
instructors and other group members were 
working in pairs to record the perfor- 
mance on a simple evaluation form." The 
finished form provided a record of each 
person's donning sequence, time to com- 
pletion of critical tasks, total time, 
and any errors made. 

Table 5 provides summary data from 12 
of these groups — 5 for the Draeger, 4 for 
the Ocenco, 2 for the CSE, and 1 for the 
MSA. It is important to note that the 

6 See "Training in the Use of the Self- 
Contained Self-Rescuer," by H. P. Cole 
and C. Vaught, later in these 
proceedings. 



TABLE 5. - Summary of data collected from SCSR donning workshops 



















Prior 


Perfect 


SCSR type 


Test 
date 


Critical time, s 


Secondary time, s 


donni 


ng 


donning 


and site 


N 


Mean 


SD 


N 


Mean 


SD 


Mode 2 


No. 3 


sequence, 






















% of total 


Draeger: 






















E. Kentucky. . . . 


1/22 


7 


17.00 


5.77 


7 


55.00 


20.78 


NAp 


NAp 


28.57 




1/28 


27 


23.89 


10.61 


27 


64.70 


29.08 


3 


12 


62.96 




1/29 


15 


20.47 


4.93 


15 


52.20 


19.18 





11 


53.33 


W. Kentucky.... 


3/18 


16 


16.25 


4.97 


17 


41.12 


17.09 





6 


22.22 




3/19 


17 


17.53 


6.71 


18 


59.17 


19.45 





11 


38.89 


Ocenco: 






















E. Kentucky.... 


1/22 


11 


26.27 


5.87 


11 


79.45 


26.16 


NAp 


NAp 


63.64 




1/29 


11 


33.73 


10.00 


11 


82.45 


24.11 





9 


45.45 


W. Kentucky. . . . 


3/18 


16 


26.44 


5.66 


15 


69.06 


25.42 


0,1 


3,3 


4 11.76 




3/19 


17 


38.64 


11.10 


19 


84.32 


19.08 





16 


47.37 


CSE: E. Kentucky 


1/22 


9 


21.67 


4.77 


9 


68.88 


17.95 


NAp 


NAp 


66.67 




1/29 


16 


24.94 


11.39 


16 


62.44 


20.91 





9 


64.71 


MSA: E. Kentucky 


1/29 


10 


17.90 


5.15 


10 


51.50 


14.35 





8 


50.00 



NAp Not applicable. 
Mode = most frequent 
more than once. 

3 No. = number of peopl 

Of the 17 trainees, 

this deviates from the p 



Experience with this model, 
occurring value in a set where different 



values may occur 



e who gave the modal response for their group. 

9 adjusted the straps before donning their goggles. 

erfect sequence, it is not a critical error. 



Although 



33 



TABLE 6. - Mean times and standard deviations for 
critical and secondary donning tasks by type 
of SCSR 1 , seconds 





Draeger 


Ocenco 


CSE 


MSA 


Critical tasks: 


20.47 
4.93 

52.20 
19.18 


33.73 
10.00 

82.45 
24.11 


24.94 
11.39 

62.44 
20.91 


17.90 


Standard deviation 
Secondary steps: 


5.15 
51.50 


Standard deviation 


14.35 


' TT/-V.- /-. 1 .-. ,7. ^ /-> «-. s*nnAii~t-n. 


A 1 /OQ/RA 









data represent the first hands-on SCSR 
experience for most of these people. 
Therefore, the performance results must 
be related to instructional procedures 
rather than to practice with the units. 
Some of the more intriguing findings are 
discussed in the following sections. 

Completion of Critical Tasks 

Inspection of the mean donning times 
for critical tasks suggest that the sim- 
plified procedure results in more rapid 
completion. In addition, an examination 
of the evaluation forms revealed that the 
performance also tended to be smoother 
than the trials of the subjects in the 
initial study. There were fewer task 
interruptions, and most steps were done 
in the proper sequence. Very few errors 
were made in completing the three criti- 
cal steps. 

Table 6 shows the means and standard 
deviations of the critical task comple- 
tion (part) times recorded for the CSE 
group whose trial occurred on January 29, 
1986. Comparison of these values with 
those in table 4 reveals that the new 



approach has great promise in improving 
SCSR donning efficiency. Even the mean 
time (44.9 s) for completion of critical 
steps required by miners in the initial 
treatment group far exceeded the average 
of those in the CSE group of January 29, 
1986. Since both of these groups had had 
the new position and simplified sequence 
demonstrated to them, these large differ- 
ences are undoubtedly due to the improved 
and more explicit instruction developed 
after the first experiment. 

Completion of Secondary Tasks 

Using the same two groups to compare 
overall proficiency is also encouraging. 
Their difference in mean total donning 
time (127.4 versus 62.4 s) is even great- 
er than their difference in average time 
needed to do the three critical tasks. 
In addition, as can be seen in table 5, 
the percentage of those who turned in a 
perfect trial with the CSE's on January 
29, 1986 (64.71%) is higher than the per- 
centage of initial treatment group mem- 
bers who were able to meet the absolute 
minimum for survival (56.25%). 



DISCUSSION 



The complexity of existing instruc- 
tional approaches, combined with the 
infrequency of hands-on training, con- 
tributes significantly to miners' diffi- 
culties in getting the SCSR on flawlessly 
and rapidly. The research reported in 
this paper suggests a more efficient don- 
ning procedure. The data contained in 
table 5, especially the percentages of 
each group having a perfect sequence on 



the first trial, are encouraging. Much 
remains to be done, however. 

Two important issues have not been 
addressed in these or earlier studies. 
First, it is not known how well or how 
long miners retain their skills in don- 
ning SCSR's. The optimum training neces- 
sary to achieve and maintain high levels 
of proficiency needs to be empirically 
determined. Then, recommendations to the 



34 



industry can be made based on an under- 
standing of what constitutes an effec- 
tive and valid approach. Second, the 
present research has identified donning 
tasks that are time-consuming, are diffi- 
cult to perform, and/or result in fre- 
quent errors. This information can as- 
sist in the improvement of SCSR designs. 



Well-controlled human performance studies 
of equipment design changes can reveal 
which modifications optimize miners' don- 
ning capabilities. Continued investi- 
gation of problems in implementing the 
self-contained self-rescuer may well help 
to prevent future tragedies. 



35 



PHYSIOLOGY OF MINE ESCAPE: PERFORMANCE DECREMENTS 
DUE TO RESISTANCE BREATHING DURING THREE EXERCISE PROTOCOLS 

By Kurt Saupe 1 and Eliezer Kamon 2 



ABSTRACT 



In the event of a mine fire or ex- 
plosion, an irrespirable atmosphere is 
formed and self-contained breathing 
apparatus are necessary to support life. 
An ideal breathing apparatus would simu- 
late ambient air in every way; however, 
this has not been achieved in any type of 
portable apparatus. Apparatus that are 
used for escape are best when light in 
weight and small in size. Small size and 
light weight, however, usually result 
in apparatus that are physiologically 
stressful in other ways. The most common 
stressors of concern are levels of CO2 
and O2 , temperature, and breathing resis- 
tance. From research being conducted at 



the Noll Laboratory for Human Performance 
Research, it has been found that breath- 
ing resistance can significantly affect 
performance in a number of areas. One 
significant finding is that a given level 
of breathing resistance may negatively 
affect escape speed if the speed is high 
and yet not affect escape at a lower es- 
cape speed. Three exercise protocols 
were performed to study effects on maxi- 
mum attainable oxygen consumption rate 
and, thus, escape speed. It was found 
that the higher the exercise intensity, 
the greater the negative effect of a 
given breathing resistance. 



INTRODUCTION 



To fulfill all the potential needs of a 
worker, a respirator should not limit the 
worker's performance under a wide range 
of conditions. Some of these conditions 
include low-intensity steady-state exer- 
cise, short-duration high-intensity exer- 
cise, and gradually increasing work to 
ventilatory exhaustion. These three con- 
ditions place different demands on respi- 
rators. Resistance is the stressor that 
seems to have the greatest effect on the 
standard measures of performance, such as 
maximum attainable speed of travel. This 
is probably due to the lower attainable 
ventilation rate, and consequently, lower 
attainable oxygen consumption rate, so 
that the worker is forced to slow down. 
Conclusions about the amount of resis- 
tance that can be tolerated before a per- 
formance limitation is seen may well be 

' Graduate student. 

2 Prof essor . 
Penn State University, Noll Laboratory 
for Human Performance Research, Univer- 
sity Park, PA. 



different depending upon the intensity of 
exercise used to evaluate the resistance. 
The purpose of this investigation was 
to quantify the performance decrements 
caused by resistance breathing during a 
simulated coal mine escape. Since there 
is no one protocol that adequately simu- 
lates all the possible scenarios that 
might be encountered during an emergency 
mine escape, three different escape pro- 
tocols were examined. These three proto- 
cols were chosen both to represent a wide 
range of demands on the respirator and to 
give insight into the physiological mech- 
anisms responsible for the performance 
decrements. The three protocols used 
were — 

1. A 2-mile run for time at a maximum 
(variable) self-paced speed. 

2. A progressive exercise test to 
exhaustion. 

3. An hour-long walk at the maximal 
speed-grade combination (fixed) that 
could be maintained for the hour. 



36 



EXPERIMENTAL DESIGN AND TEST METHODS 



SUBJECTS 

Male subjects were recruited from the 
Perm State University area. Subjects 
were either undergraduates, graduate stu- 
dents, or staff of Penn State. Different 
subjects were used for each of the three 
protocols with some subjects taking part 
in both the hour walk and progressive 
exercise tests. Subject characteristics 
are listed in table 1. 

METHODS 

The physiological variables of heart 
rate, ventilation rate (VE), fraction of 
expired O2 (FEO2), fraction of expired 
CO2 (FEC0 2 ), and pressure at the mouth 
were continuously measured and recorded 
on-line via a PDP-11 (or PDP-8) computer 
and in-house software. From these vari- 
ables, rate of O2 consumption (VO2), rate 
of CO2 production (VCO2), respiratory 
quotient (R), and VE/VO2 were continuous- 
ly calculated. 

The inspired and expired resistances 
were caused by inserting a small-diam- 
eter, 5-cm-long tubing segment in both 
the inspired and expired sides of the 
data collection system. The resistance 
of the system without these restrictive 
segments was 1.5 cm H2O at 120 L/min. 

PROCEDURES 

Maximal aerobic capacity was measured 
using a separate progressively graded 

test to exhaustion, 
preliminary medical 



treadmill exercise 
as part of a 
examination. 



The short-term exercise called for 2.5% 
increases in the grade of the treadmill 
every 4 min. The data over the last 
minute of exercise at each grade were 
used to represent the steady state value 
for that exercise intensity. 

The prolonged exercise was performed 
at the maximum speed and grade that could 
be maintained for 1 h by the subject. 
One hour of exercise was first performed 
without resistance to breathing; the ex- 
ercise was repeated next with a randomly 
selected resistance to breathing. If 1 h 
of exercise could not be accomplished, 
the subject returned on another occasion 
to attempt the same resistance at an ex- 
ercise intensity obtained by a reduction 
in the grade of the treadmill. This was 
repeated until the hour of exercise was 
completed, and that exercise intensity 
was considered the highest sustainable 
for the given resistance. 

The 2-mile runs for time were performed 
so that subjects had a visual display 
of how far they had run. Subjects were 
able to control their speed by giving a 
thumbs-up or thumbs-down to an investiga- 
tor who was sitting at the treadmill con- 
trol panel. Four, all-out 2-mile runs 
were initially done by each subject with 
no resistance to establish a reliable 
baseline. When these runs were com- 
pleted, subjects ran a low-resistance 
(10 cm H 2 at 120 L/min) and a high- 
resistance (34 cm H2O at 120 L/min) all- 
out 2-mile run in a randomly assigned or- 
der. These self-paced, all-out runs were 
performed a week apart to minimize any 
training effect. 



TABLE 1. - Mean subject characteristics 
(Standard deviation in parentheses) 



Exercise protocol 


N 


Age, 
yr 


Height, 
cm 


Weight, 
kg 


VO2 max, 
L/min 


Short-term progressive 


5 
7 
5 


26 (2) 
26 (4) 
24 (3) 


177 (8) 

178 (7) 
178 (4) 


72 (9) 
75 (10) 

73 (9) 


3.95 (0.77) 
3.77 (.56) 




4.20 (.60) 



37 



RESULTS 



The problem of how to best quantify the 
resistance-induced performance decrements 
so that they could be compared across all 
three protocols was addressed by express- 
ing the V0 2 that could be maintained dur- 
ing a resistance trial as a percentage of 
the V0 2 that could be maintained during a 
no-resistance control trial. If, for ex- 
ample, a subject could maintain a V0 2 of 
4 L/min during a no-resistance 2-mile run 
and a V0 2 of 3 L/min during a 2-mile run 



with a resistance of 34 cm H 2 at 120 
L/min, the performance decrement would be 
expressed by stating that he or she could 
maintain a V0 2 of 75% of the control val- 
ue with the 34-cm H 2 at 120-L/min resis- 
tance. These data suggest that as the 
task performed by the subject becomes 
increasingly difficult (higher percentage 
of V0 2 max), the performance decrement 
that one sees with a given resistance 
becomes greater. Figure 1 shows the 



100 






m 
o 

o 
■> 

_J 

o 

on 



O 

o 
o 



KEY 

H 2-mile run 

|~l 1-hour walk 

Progressive exercise 




20 30 40 50 

RESISTANCE, cm water at 120 L/min 

FIGURE 1.— Percent of control V0 2 obtained versus breathing resistance for three exercise intensities. 



60 



38 



percentage of a control trial VO2 that 
could be maintained over a range of re- 
sistances for the three protocols. The 
somewhat nebulous term "maximal maintain- 
able VO2" was defined differently for 
each of the three protocols. For the 
progressive exercise test, this terra was 



defined as the VO2 at the highest obtain- 
able exercise intensity. For the hour- 
long walks it was defined as the mean 
V0 2 between minutes 15 and 45. For the 
2-mile runs it was defined as the mean 
V0 2 from minute 5 to the end of the 2 
miles. 



DISCUSSION 



These data illustrate a principle that 
is often overlooked when one looks at 
the level of breathing resistance allow- 
able in a specific breathing apparatus. 
This principle can best be illustrated 
by imagining what would happen to an in- 
dividual whose only source of air was 
through a soda straw. The individual 
would be able to perform tasks such as 
reading and writing with no noticeable 
performance decrement. If the individual 



were asked to perform tasks of increased 
physical demand, he or she would find 
that the more strenuous the task (in 
terras of VO2 required), the more he or 
she was encumbered or restricted. 

Any standard or specification defin- 
ing the maximum allowable resistance to 
breathing of a respirator should be spe- 
cific to the intensity of physical activ- 
ity that the users of this respirator are 
expected to maintain. 



CONCLUSIONS 



Breathing resistance levels that sig- 
nificantly impair performance at a maxi- 
mal work intensity may not impair per- 
formance at a lesser work intensity. 
Breathing apparatus that are designed to 
be used at low or medium work intensi- 
ties, therefore, might be permitted to 
have higher breathing resistance levels 
than apparatus that are expected to be 
used at high work intensities. 

The present limit on exhalation breath- 
ing resistance is 5.1 cm H2O at 120 L/min 
flow; the limit for inhalation resistance 
is 10 cm minus this value, or 4.9 cm. If 
one is willing to accept a 5% decrease in 
maximal maintainable VO2 during a 1-h, 
maximal-effort escape, from the evidence 
presented in the figure, there is no rea- 
son why it should not be permitted to al- 
low three times the presently permitted 
exhalation resistance. The 2-mile run, 
taking substantially less time, suffers a 
greater decrease in maximum attainable 
VO2 of approximately 13%. 



Because human subjects can tolerate 
high stressors for a short period of 
time, it is currently a popular belief 
that short-duration apparatus, such as 
those for escape, can be permitted to 
stress the subject more than longer dura- 
tion apparatus, such as those used for 
rescue. This philosophy may not apply 
well to breathing resistance, however. 
If performance is not to be limited, 
breathing resistance limits may actually 
need to be lower for escape than for res- 
cue apparatus. In other words, an escape 
apparatus, if expected to be used at 
a high work intensity, should have low 
breathing resistance so as not to nega- 
tively impact performance. A breathing 
resistance of 8 cm H2O has been proposed 
for both inhalation and exhalation resis- 
tances for the belt-wearable oxygen self- 
rescuer being pursued by the Bureau of 
Mines and MSHA. 



39 



SECOND-GENERATION SELF-CONTAINED SELF-RESCUERS 
By John G. Kovac 1 



ABSTRACT 



It appears to be technologically fea- 
sible to develop a second-generation 
SCSR that is approximately twice the size 
and weight of an FSR and that has a 
rated duration of 1 h. This paper summa- 
rizes proposed performance criteria, test 



methods, and approval and certification 
procedures for second-generation SCSR's. 
If designed and developed to meet the 
proposed standards, the resulting SCSR 
would be safe and reliable, and could be 
worn by a miner as personal equipment. 



INTRODUCTION 



Federal mining regulations (30 CFR 
75.1714) require that every person who 
goes into an underground coal mine in the 
United States must be supplied with a 
self-contained self-rescuer (SCSR). An 
SCSR is an emergency breathing apparatus 
designed for use during mine escape. It 
must be capable of providing a breathable 
atmosphere, regardless of the ambient en- 
vironment, and it must have a rated dura- 
tion of 1 h. Only SCSR's approved by the 
Mine Safety and Health Administration 
(MSHA) and the National Institute for Oc- 
cupational Safety and Health (NIOSH) can 
meet the provisions of the regulations. 

Four models of MSHA- and NIOSH-ap- 
proved, 1-h-duration SCSR's are commer- 
cially available: CSE AU-9A1, Draeger 
OXY-SR 60B, MSA 60-min SCSR, and Ocenco 
EBA 6.5. In order to meet the 1-h-dura- 
tion requirement, all of the SCSR's are 
closed-circuit breathing apparatus. Both 
the Draeger OXY-SR 60B and the MSA 60-min 
SCSR use potassium superoxide (KO2), a 
solid chemical, to generate O2 and remove 
C0 2 . The CSE AU-9A1 and the Ocenco EBA 
6.5 store O2 as a compressed gas and use 
lithium hydroxide (LiOH) to absorb CO2. 
All of the 1-h-duration SCSR's are much 
larger and heavier than the conventional 
filter self-rescuer (FSR), which a miner 
wears on his belt as personal protective 
equipment. Unlike SCSR's, FSR's protect 
only against low levels of CO. 

'Supervisory mechanical engineer, 
Pittsburgh Research Center, Bureau of 
Mines, Pittsburgh, PA. 



Because of the large size and weight of 
the current 1-h SCSR's, miners and mine 
operators have elected to either store or 
carry and store SCSR's in daily oper- 
ational use rather than wear SCSR's as 
personal protective equipment. 

It appears to be technologically feasi- 
ble to develop a second-generation SCSR 
that is approximately twice the size and 
weight as an FSR, and that has a rated 
duration of 1 h, if testing and certi- 
fication criteria are changed. Such an 
apparatus has been designated as a per- 
son-wearable self-contained self-rescuer 
(PWSCSR). A PWSCSR meeting these re- 
quirements could be worn on a miner's 
belt and replace the FSR. The mining in- 
dustry, mine workers, breathing apparatus 
manufacturers, and MSHA are interested in 
an emergency breathing apparatus of this 
kind. 

However, much work remains to be accom- 
plished before prototype technology can 
be expected to function in a reliable 
manner. Additional research and develop- 
ment must be done to guarantee that the 
devices will provide safe and appropriate 
levels of life support capability and 
will be sufficiently rugged and mine- 
worthy to serve as a replacement for 
FSR's. Practical deployment options, as 
well as miner training in the use of 
PWSCSR's must also be investigated. 

The purpose of this paper is to summa- 
rize proposed criteria and test proce- 
dures for PWSCSR's that would provide 
safe performance, be rugged for under- 
ground use, and be within desirable 



40 



physical limitations. The proposed test- 
ing and certification criteria for 
PWSCSR's are presented in the appendix. 

The information presented in this paper 
is based on the technical recommendations 
of the Person-Wearable SCSR Task Force, 
which was an interagency task force com- 
posed of representatives from MSHA, the 
Bureau, and NIOSH. The task force used a 
variety of sources in formulating its 
recommendations, including current re- 
search findings, conversations with res- 
pirator manufacturers and other technical 
specialists, and discussions with repre- 
sentatives of miners and mine operators. 

DEFINITION OF ESCAPE-ONLY DEVICE 

There are emergencies in which the need 
for an escape breathing apparatus is im- 
mediate. In these situations, an indi- 
vidual who has an apparatus on his or her 
person is more likely to survive than an 
individual who has an apparatus located 
a distance away. Whether an individual 
wears an escape breathing apparatus or 
not depends to a large degree upon the 
physical requirements of the job and the 
size of the escape apparatus. 

An escape-only device is designed to 
supply, in an emergency, an atmosphere 
that will permit the user to escape to a 
safe environment. The ideal escape-only 
device is one that is worn by the indi- 
vidual at the job, is rugged so that it 
will survive its environemnt and perform 
its function, and is safe for its in- 
tended use. 

PWSCSR's are escape-only devices in- 
tended for use in underground coal mine 
emergencies. 

NEW PERFORMANCE CRITERIA 

The proposed performance criteria focus 
mainly on defining safe, physiologically 
defensible stressor levels for PWSCSR's. 
Four physiologically important variables 
are considered: carbon dioxide (CO2) 
concentration, oxygen (O2) concentration, 
breathing resistance, and inhaled gas 
temperature. 



CO 2 Level 

The present requirement for a 1-h es- 
cape apparatus is no more than 1.5% CO2 
in inspired air, during the course of 
person-testing when sampling breathing 
gases. Breathing gases are sampled dur- 
ing rest intervals, so gas concentrations 
are monitored intermittently. 

The proposed requirement for CO 2 
stressor levels is to raise the 1.5% CO2 
maximum inhaled concentration to 3.0% for 
a 1-h escape apparatus, while monitoring 
continuously. The new stressor level is 
to be determined by time-averaging the 
inhaled CO2 levels over the entire dura- 
tion of the apparatus. When testing 
presently approved 1-h-duration SCSR's, 
it was observed that some apparatus ex- 
hibited inhaled CO2 levels exceeding 4% 
during certain exercise levels and near 
the end of life. This testing utilized 
continuous monitoring, unlike that pres- 
ently conducted at NIOSH. Therefore, in 
addition to a 3% inhaled CO2 average lev- 
el for a 1-h apparatus, a termination 
peak concentration of 8% CO2 for a single 
breath and a 1-min average concentration 
of 6% CO2 are added for safety. 

Oxygen Level 

The oxygen concentration has been in- 
creased from 19.5% to 20.9% after the 
first 3 min. In addition, a 17% minimum 
O2 concentration is required for the 
first 3 min. The reason for these two 
requirements is to eliminate the need for 
a self-starter. All presently approved 
1-h apparatus exceed 21% O2. 

Breathing Resistance 

The present standard measures breath- 
ing resistance utilizing a breathing 
machine as specified in 30 CFR 11.85-3. 
The maximum resistance for exhalation is 
51 mm H2O or less, and the maximum for 
inhalation is 100 mm H2O minus the exha- 
lation resistance. 



41 



The new proposal allows for a maximum 
of 80 mm H2O for both inhalation and ex- 
halation resistance when measured during 
the time-duration test. During the high- 
demand test, the allowable resistance 
levels are 300 mm H2O for inhalation and 
200 mm H2O for exhalation. 

Inhaled Gas Temperature 

The present inhaled gas temperature re- 
quirement divides the inspired air into 
two categories, from 0% to 50% RH (rela- 
tive humidity), and the other from 50 to 
100% RH. 

The new criteria allow for alternate 
wet bulb temperature measurements that 
automatically take into account tempera- 
ture and relative humidity. Owing to the 
complexity of measuring wet bulb tempera- 
ture, it may be more practical to monitor 
both relative humidity and dry bulb tem- 
perature of inspired air and use conver- 
sion charts. Both options are provided 
for in the criteria. 

Time-Duration Test 



The Escape Duration Analysis Task Force 
has determined that 80 L of usable O2 
will allow 95% of the miners to escape 
from working sections to fresh air. This 
quantity of O2 will last 60 min when con- 
sumed at a rate of approximately 1.35 
L/min. The 50th percentile miner, when 
performing the 1-h Man Test 4 (30 CFR 
11), will use approximately 80 L O2. 

The proposed time-duration test uses a 
human subject who works at a fixed rate 
of 1.35 L/min O2. This is a simple and 
repeatable test. According to the pro- 
posed procedure, a human subject would be 
placed on a treadmill, and the treadmill 
speed would be adjusted to require a met- 
abolic demand of 1.35 L/min O2. After 
the treadmill speed for a human subject 
had been determined, the human subject 
would remount the treadmill with the ap- 
paratus to be tested. This approach sim- 
plifies the time-duration test and pro- 
vides repeatability. The apparatus being 



tested would have to supply the wearer 
with a breathable atmosphere for 1 h. 

High-Demand Test 

Man tests contained in 30 CFR 11 pro- 
vide information on the function of 
breathing apparatus at various work 
rates. The new time duration test is 
performed at a fixed work rate. To de- 
termine how well a breathing apparatus 
functions at various work loads, a high- 
demand test has been proposed. 

During the high-demand test, a human 
subject walks or runs in place on a 
treadmill, varying the rate of O2 con- 
sumption, according to a predetermined 
schedule of exercises. The high-demand 
test ensures that the apparatus will 
function across a set of work rates. 
Stressor levels are monitored continu- 
ously to ensure a breathable atmosphere 
at the different work rates. 

The rated duration of the units is es- 
tablished by the time-duration test and 
need not be achieved in the high-demand 
test. Time is monitored to ensure that 
the units can be worn for a minimum time 
period at the elevated work rates of the 
high-demand test. The minimum time for 
a 1-h unit during the high-demand test 
is 40 min. The time-duration and high- 
demand tests provide a simple means to 
objectively determine performance charac- 
teristics of the units. 

Ruggedness Tests 

Ruggedness tests are intended to deter- 
mine raineworthiness of PWSCSR's that 
would be worn as personal equipment on a 
daily basis. 

There are four ruggedness tests to sim- 
ulate a range of environmental conditions 
likely to be found in underground coal 
mines. The first test exposes a PWSCSR 
to high and low temperatures. The second 
and third tests expose an apparatus to 
shock and vibration. The fourth test is 
a submersion test designed to evaluate 
the integrity of the protective case. 



42 



All four tests are applied to an appa- 
ratus. Afterwards, the respirator is 
inspected for safe operation, and then 
performance-tested. 

Human Factors Test 

The human factors test addresses ergo- 
nomic considerations for comfort and 
wearability of such apparatus. The human 
factors test is designed to evaluate the 
unit while human subjects are performing 
simple tasks that may be encountered dur- 
ing an escape. As in the time-duration 
and high-demand tests, physiological var- 
aibles are monitored continuously during 
the human factors test. 

The time required to perform these 
tests is not related to the rated dura- 
tion of the units. A 1-h unit is re- 
quired to be worn and perform the func- 
tions listed for 33 min. This time 
requirement is to assure that the per- 
formance of these activities does not re- 
duce the wearing of time of the units. 

ADMINISTRATIVE ISSUES 

Administrative changes to current ap- 
proval and certification procedures are 
recommended. 



Third-Party Testing 

The most significant administrative 
change is to allow third-party testing of 
respirators. A manufacturer can test his 
own apparatus, or use an independent lab- 
oratory. The Government reserves the 
right to witness all tests at the loca- 
tion specified by the manufacturer. The 
Government will review the test results, 
and, if necessary, require retesting. 

Special Use Escape-Only Devices 

The technical specifications developed 
by the Task Force apply to PWSCSR's, 
which are escape-only devices intended 
for use in underground coal mine emer- 
gencies. The proposed approval and cer- 
tification criteria encourage other in- 
dustries or organizations to recommend 
alternate performance criteria, test 
methods, and procedures for specialized 
escape-only devices. 

Training 

Hands-on training is critical for the 
successful deployment of PWSCSR's. Manu- 
facturers are required to have realistic 
training units available for purchase. 



CONCLUSIONS 



The PWSCSR Task Force has developed 
proposed standards for second-generation 
SCSR's. These recommendations include 
new performance criteria, test meth- 
ods, and procedures for approval and 



certification. If designed and developed 
to meet the proposed standards, the re- 
sulting PWSCSR would be safe and reliable 
and could be worn by a miner as personal 
equipment. 



APPENDIX. —PROPOSED TESTING AND CERTIFICATION CRITERIA FOR PWSCSR'S 



43 



A. TEST PROCEDURES 



C-l. 2 Levels 



MSHA and the Institute reserve their 
right to witness all tests at the loca- 
tion specified by the equipment manufac- 
turer. The equipment manufacturer will 
reimburse MSHA and the Institute for 
travel, subsistence and incidental ex- 
penses of its representatives in accord- 
ance with Standardized Government Travel 
Regulations. MSHA and the Institute will 
be notified at least two months prior to 
testing in order to determine if instru- 
mentation is adequate to perform tests. 
The notification will include one unit 
that represents the escape respirator to 
be tested. The equipment manufacturer 
will be responsible for all clearances 
necessary at the test facility for MSHA 
and Institute personnel. The equipment 
manufacturer is responsible for supply 
test reports, test procedures, instrumen- 
tation specifications, calibration trace- 
ability, instruction manual and other 
documentation as requested by MSHA or the 
Institute. MSHA or the Institute may re- 
quire instrumentation capability to be 
verified prior to or during testing, by 
calibration standards, calibration gases, 
or by the testing of a respirator whose 
characteristics are known. 

B. UNITS REQUIRED FOR TEST 

MSHA and the Institue may require sub- 
mittal of up to 12 units for testing. 
The applicant will not be charged for 
testing. 

Units must meet the criteria and the 
tests outlined in "E" through "H-2". If 
the units are prototypes, six production 
units will be tested when available. The 
production units must meet all approval 
and certification criteria. 

C. CRITERIA 

Units must meet all the criteria speci- 
fied in "C-l through -4." 



Inhaled oxygen will not fall below 17% 
(dry atmosphere) during the first 3 min 
of operation. After 3 min, the minimum 
2 level will not be less than 20.9% 2 
(dry atmosphere). During respirator 
testing, the 2 will be monitored contin- 
uously at the mouthpiece by a sensing 
unit with at least a 90% response within 
100 ms and an accuracy of ±0.1% 2 . 

C-2. C0 2 Levels 

C0 2 will be monitored continuously at 
the mouthpiece and the average inhaled 
C0 2 concentration will not exceed 3% over 
the time rating of the unit. This value 
will be an arithmetical average of C0 2 
concentration over the inhalation cycle. 
The arithmetical average of the C0 2 level 
for any 1-min-time period will not ex- 
ceed 6.0% for the inhalation cycle; and 
for a single breath, the average will not 
exceed 8%. 

C-3. Temperature Levels 

Inhalation temperatures will not exceed 
45° C wet bulb temperature. If wet bulb 
temperature cannot be measured at the 
test location by instrumentation having 
a 90% response within 500 ms with an 
accuracy of ±1° C, the temperature will 
meet the requirements in 30 CFR, Section 
11.85-18(c). 

C-4. Pressure Limitations 

The exhalation pressure will not exceed 
80 mm H2O, and the inhalation pressure 
will not exceed 80 mm H 2 measured at the 
mouthpiece with a breathing machine as 
described in 30 CFR 11.85-3. Pressure 
will be continuously monitored during the 
time duration and high— demand tests and 
will not exceed 300 mm H 2 for inhalation 
and 200 mm H 2 for exhalation when mea- 
sured by a sensing unit with at least a 



44 



90% response within 5 ms and an accuracy 
of ±1 mm. 

D. GENERAL CRITERIA 



the manufacturer displayed on the labels, 
and will meet or exceed all criteria 
listed for the specified duration as 
evaluated in "F. Time Duration Test." 



Devices are intended for escape only 
and will be made as small and lightweight 
as possible to improve the user-wearing 
capability. 

D-l. Special-Use Escape Devices 

Escape devices for use in specialized 
areas or industries will be designed for 
use during escape from those environ- 
ments expected to be encountered. The 
following four examples of specialized 
areas/industries are in no way intended 
to limit the number of users or types of 
testing involved. Users with special re- 
quirements should meet with the Institute 
and MSHA to develop performance criteria, 
test methods and procedures to meet their 
needs, which will then be distributed to 
all "interested parties." Limitations 
will be identified on the manufacturers' 
labels. 

1. Fire Service - Fire service escape 
devices will have fire-resistant exposed 
parts, and be self-contained devices. 

2. Chemical Industry - Chemical indus- 
try escape devices may have exposed parts 
that must be resistant to chemical vapors 
expected to be encountered in the spe- 
cific environment. 

3. Mining Industry - Mine escape de- 
vices will be self-contained, and must be 
worn by miners as part of their personal 
protective equipment. 

4. U.S. Naval Shipyards - Confined 
space escape devices will be self-con- 
tained, have fire resistant parts and 
hood, provide means for carrying by 
shipyard personnel, and be streamlined, 
small, and lightweight to allow rapid es- 
cape through 20-in accesses. 

D-2. Time Duration Test 



E. TEST METHOD 

The 12 units will be randomly divided 
into four groups of three units each. 
These groups will be tested as specified 
in "F" through "H-2." 

E-l. Human Subject Testing Procedure 

The equipment manufacturer is responsi- 
ble for all testing and test equipment, 
as well as obtaining the human subjects, 
appropriate medical releases, pretesting 
physicals, and all other necessary physi- 
cal and documentary evidence for conduct- 
ing a safe human subject testing proce- 
dure on these apparatus. Appropriate 
medical attendance at the human subject 
testing is the responsibility of the 
equipment manufacturer. 

E-2. Human Subject Profile 

a. Test subject Type A will be an in- 
dividual of at least 100 kg body weight. 

b. Test subject Type B will be an 
individual between 65 and 100 kg body 
weight. 

c. Test subject Type C will be an 
individual with a maximum body weight of 
65 kg. 

F. TIME DURATION TEST 



Three units will be 
subjects as follows: 



evaluated on human 



a. Human subjects (one of each subject 
type) will be mounted on a treadmill. 
The speed of the treadmill, for each hu- 
man subject, will be adjusted to obtain 
the following minimum oxygen consumption 
rates, based on the apparatus time rat- 
ing, according to the following table: 



Escape-only devices will have the time 
duration of the apparatus as specified by 



45 



TABLE A-l. - Apparatus time rating 



G-3. Shock Tests 



10. . . 


Time, 


min 


O2 consumption 
rate, L/min 

2.1 


15. . . 






2.0 


30. . . 






1.7 


45. .. 






1.5 











For example, if a 60-min device is to be 
tested, each human subject type would 
mount the treadmill and the treadmill 
speed would be adjusted until the oxygen 
consumption rate is 1.35 L/min. The 
treadmill speed for each human subject 
type would then be documented. 

b. A human subject, wearing the appa- 
ratus to be tested, will mount a tread- 
mill with the speed preset to at least 
the value determined in "a" above for 
that subject. Treadmill speed must meet 
or exceed the value determined in "a" for 
rated duration of the apparatus. 

c. All units will meet or exceed the 
criteria listed under "C" for the time 
duration specified. 

G. RUGGEDNESS TESTS 

Three units with protective cases will 
be tested as specified in "G-l through 
6," and in the sequence listed. 

G-l. Temperature Test 

Temperature tests will be conducted by 
exposure of all three units to a temper- 
ature of at least -30° C for 8 h. All 
three units will thereafter be stabilized 
at room temperature before exposure to a 
temperature of 71° C for 4 h. After ex- 
posure to a temperature of 71° C, all 
three units will then be stabilized at 
room temperature. 

G-2. Vibration Test 

The three units will be vibrated as per 
MIL-STD-810B. 



The three units will be dropped from 
a height of 1 m onto a concrete floor. 
Each unit will be dropped a minimum of 
six times, at least once on each axis. 

G-4. Water Submersion Test 

The three units will be stabilized at a 
room temperature of 22° C±2°, and then 
will be submerged in a water bath until 
they are completely covered with water, 
for a period of 1 min. The water bath 
must be at a temperature of 15° to 18° C. 
Upon completion of this test, all units 
must be intact without water penetration 
to the unit interior. 



G-5. Inspection 

The three units will be 
to ensure they are in safe 
condition. 



inspected 
operating 



G-6. Time Duration Test for 
Environmentally Treated Units 

All units will meet or exceed the cri- 
teria listed under "C" for the time dura- 
tion specified. 

H. OTHER TESTS 

H-l. High-Demand Test 

One human subject of each profile type 
(total of 3), wearing an apparatus, will 
mount a treadmill which will be run at 
the conditions specified in the High- 
Demand Test table. 

a. Temperature will be monitored dur- 
ing this test and will meet the require- 
ments in "C-3." 

b. Oxygen, CO2, and pressure will be 
continuously monitored and will meet 
the criteria in "C-l, C-2, and C-4" 
respectively. 

c. All subjects must complete the de- 
mand test. 



46 



TABLE A-2. - High-demand test 



Activity 



Walk 

Run, uphill. 

Walk 

Run 

Walk 

Run , 

Walk , 

Run, uphill. 

Walk , 

Run , 

Walk 



Service time, min 



10 



2 
1 

2 
3 
2 

NAp 
NAp 
NAp 
NAp 
NAp 
NAp 



15 



2 
1 
2 
3 

2 
2 
3 

1 
NAp 
NAp 
NAp 



30 45 60 



2 
1 
2 
3 
2 
2 
3 
1 
11 
2 
6 



2 
1 
2 
3 
2 
2 
3 
1 

11 
3 

10 



Walk - 0% grade, 3.0 mi/h; 

Run - 0% grade, 5 mi/h; 

Run uphill - 15% grade, 5 mi/h. 

H-2. Human-Factors Test 

One human subject of each profile type 
(a total of 3) will perform the tests as 
specified in the Human Factors Test table 
after donning a unit. 

a. Carbon dioxide and oxygen will be 
continuously monitored and will meet 
the requirements in "C-l and C-2" 
respectively. 

b. Due to the short service times of 
the 10- and 15-min units, the sequence 
of activities for human factors testing 
will be divided into two equal groups. 
At least one test subject will perform 



the activities of each group. All three 
test subjects will perform all the activ- 
ities listed for the 30-, 45-, and 60-min 
units. 

TABLE 3. - Human factors test 



Activity 



Bending motion 

Stand 

Stretching 

Stooped walking 

(127 cm, 2.5 mi/h) 
Crawl (0% grade, 

1.5 mi/h) 

Carry 20 kg (0% 

grade, 3 mi/h). . . . 

Twisting 

Lie on back side, 

front 

Duck walk 

Walk (0% grade, 

3 mi /h ). 

Run (0% grade, 

5 mi/h) 



Service time, min 



11 

2 

2 
2 

2 

2 

2 

2 

2 
2 



2 



15 



30 



45 



60 



I. TRAINING MATERIAL 

Manufacturers who obtain an approval 
are required to have available to users 
training units that closely duplicate the 
stressor levels that the approved unit 
exhibits, and training manuals. 



DEVELOPMENT OF A LOW-PROFILE RESCUE BREATHING APPARATUS 
AND A MINE RESCUE TEAM HELMET 

By Nicholas Kyriazi 1 



ABSTRACT 



The Bureau of Mines has funded the de- 
velopment of two items of mine rescue 
team equipment in order to make mine res- 
cue missions safer and more efficient. A 
2-h breathing apparatus was developed 
with the goals of low profile, light 
weight, positive pressure, cooler breath- 
ing air, and low breathing resistance. 
These goals were achieved through the use 
of efficient design, proper choice of 



materials, dual spring-loaded breathing 
bags, and an internal heat exchanger. 
The apparatus, the LP-120, has a profile 
of 10 cm, weights 10 kg, and contains 240 
L 2 . A rescue team helmet was also de- 
veloped that combines the functions of 
full head protection, breathing apparatus 
facepiece, communications, and lighting. 
This helmet was designed to be used with 
the LP-120. 



INTRODUCTION 



Since mine rescue teams constitute a 
small market in the view of equipment 
manufacturers, their needs remain unful- 
filled when they are unique. At present, 
mine rescue teams utilize equipment that 
largely has been designed for other pur- 
poses and are hampered in their duties by 
being forced to use safety equipment that 
only marginally serves their needs. Sim- 
ply stated, the problem is that the more 
general the need, the more likely it is 



to be satisfied; whereas the more unique 
the need, the more likely it is to be 
unsatisfied. 

The Bureau is attempting to solve the 
problem of how to advance technology in 
mine rescue team equipment through sub- 
sidizing its development costs. At 
present, the Bureau is involved with two 
such developments: a low-profile rescue 
breathing apparatus and a mine rescue 
team helmet. 



DESCRIPTION OF APPARATUS 



The low-profile rescue breathing appa- 
ratus is being developed by U.S.D. Corp. 
through contract H0123008. The mine res- 
cue team helmet is being developed by 
Gentex Corp. through contract H0252050. 
Both pieces of equipment are being devel- 
oped to improve the efficiency, safety, 
and comfort of mine rescue team mem- 
bers involved in mine rescue and recovery 
missions. 

LOW-PROFILE RESCUE BREATHING APPARATUS 

Four agencies are cofunding the low- 
profile rescue breathing apparatus 
(LPRBA) contract - the U.S. Bureau of 

'Biomedical engineer, Pittsburgh Re- 
search Center, Bureau of Mines, Pitts- 
burgh, PA. 



Mines, for use by mine rescue teams on 
rescue and recovery missions in under- 
ground coal mines; the U.S. Air Force, 
for use by Air Force firefighters in 
chemical warfare f iref ighting; the U.S. 
Federal Emergency Management Agency (sub- 
group - U.S. Fire Administration), for 
use by firefighters in situations when 
long-duration apparatus are needed, such 
as in high-rise buildings, tunnels, and 
subways; and the U.S. Coast Guard, for 
use in cleaning up chemical spills or 
toxic waste dumps. 

The LPRBA is a closed-circuit apparatus 
and has a rated duration of 120 min, 
hence its name, the LP-120. Figure 1 
shows the LP-120 in its present configu- 
ration; figure 2 is a schematic of the 
apparatus. Since duration is dependent 
upon O2 use rate, the apparatus is better 



48 




Positive - pressure-biased 
demand valve \ 



Pneumatic alarm 




Spring 



KEY 
-\ — Inhaled air 
— Exhaled air 



FIGURE 1.-The LP-120. 



FIGURE 2.— LP-120 schematic. 



described as containing 240 L 02* The 
apparatus has a number of features that 
make it unique among closed-circuit 
RBA's: 

1. The most significant feature is the 
low profile of the apparatus, which is 
effectively 10 cm from the farthest pro- 
jection of the back. The actual thick- 
ness will be greater than 10 cm, but use 
of the contour of the human back keeps 
the 10-cm profile. The most widely used 
RBA, the Draeger BG-174A, has a thickness 
of 16 cm and contains 400 L O2. This is 
considered a 4-h device but is not usu- 
ally used for more than 2 h. 

2. The weight of the LP-120 is also 
a significant improvement over that of 
present apparatus. It is projected to 
weigh approximately 10 kg compared to 
16 kg for the Draeger BG-174A. 

3. The apparatus is a positive-pres- 
sure system, which means that, in most 
circumstances, the pressure in the face- 
piece remains positive compared to ambi- 
ent. This ensures that any inadvertent 



leaks will be outward and will not result 
in any inward leakage that could contami- 
nate the breathing air and endanger the 
wearer. The positive pressure is main- 
tained through the use of a biased demand 
valve and two spring-loaded bags. 

4. Dual breathing bags enable the 
breathing resistance to be split between 
inhalation and exhalation, unlike other 
closed-circuit RBA's in which most of the 
effort is placed on exhalation. This is 
because other apparatus place their sin- 
gle breathing bag in the breathing loop 
after the C02 _ absorbent canister, or CO2- 
scrubber, so that the user must force the 
air through the chemical bed on exhala- 
tion. The use of two breathing bags 
splits the work of breathing, and, be- 
cause of the pressure gradient between 
the bags on either side of the CO2- 
scrubber, some of the air flows through 
the scrubbers by itself. 

5. A lithium nitrate, phase-change, 
heat exchanger is utilized to cool the 
air after it is heated by the LiOH in the 
scrubber. 



49 



MINE RESCUE TEAM HELMET 

The major improvement offered by the 
mine rescue team helmet (MRTH) (figs. 
3-6) is that it consolidates a number of 
separate pieces of equipment produced by 
different manufacturers: the hardhat, 
the facepiece of the breathing apparatus, 
the cap lamp, and the communications sys- 
tem. All of the separate items have been 
designed to be compatible with each oth- 
er, and the MRTH has been designed to be 
compatible with the LP-120. Following 
are listed the benefits of the MRTH: 

1. The new helmet increases head pro- 
tection through the use of impact- and 
penetration-resistant materials and in- 
creased coverage at the back and sides of 
the head. 

2. Unlike a hardhat, it will not fall 
off if you lower your head. 

3. It offers a lower profile than hard 
hats. This will result in hitting the 
roof less often. 

4. The MRTH utilizes a new, smaller 
light source designed and sold by MSA. 

5. The faceplate is removable and 
attaches to the chest straps of the 



breathing apparatus when breathing pro- 
tection is not needed. See figure 6 for 
a concept drawing. 

6. A three-position switch in the com- 
munications system enables the wearer to 
speak to ambient, or the fresh air base, 
if connected to the lifeline, or to turn 
off the communications system. 




FIGURE 4.— MRTH, side view. 







FIGURE 3.-MRTH, front view. 



FIGURE 5.— MRTH, back view. 



50 





FACEPIECE HARD SHELL 
IN DONNED POSITION 



FACEPIECE HARD SHELL 
IN DOFFED POSITION 



FIGURE 6.— MRTH concept drawing. 



51 



TRAINING IN THE USE OF THE SELF-CONTAINED SELF-RESCUER 
By Henry P. Cole 1 and Charles Vaught 2 



ABSTRACT 



Researchers from the University of Ken- 
tucky and the Bureau of Mines have devel- 
oped a set of training materials designed 
to increase SCSR donning proficiency. 
The package presents a generic procedure 
for the four SCSR's in common use (CSE, 
Draeger, MSA, and Ocenco). It offers 
(1) a donning position that is easy and 
efficient, (2) a donning sequence that 
moves critical steps (those necessary to 
isolate one's lungs from the ambient 
atmosphere) up front, and (3) a set of 
simplified, easy-to-remember procedural 
rules that can help miners order the 



complex array of tasks needed to put a 
self-contained self-rescuer into use. 

This training package has been field- 
tested with 16 groups of coal industry 
people in 3 States. The preliminary data 
suggest that the generic procedure is 
more efficient than training approaches 
currently in use. Additionally, the sum- 
mary statistics indicate a need for con- 
sistent and thorough training that in- 
cludes hands-on performance trials. The 
optimum interval for such activities has 
yet to be determined. 



The air in the immediate area of an un- 
derground coal mine explosion or fire may 
contain so little O2 and such high levels 
of CO that filter self -rescuers would be 
ineffective. Under such conditions, sur- 
vivors would have to don the self-con- 
tained self-rescuers (SCSR's) rapidly and 
flawlessly. Miners located at some dis- 
tance from an explosion or fire might 
have more time to put their SCSR's into 
use, but a mine's ventilation system can 
quickly sweep deadly levels of smoke and 
CO into relatively distant places. In 
either case, proficient donning of the 
device is critical. 

Researchers from the University of 
Kentucky and the Bureau of Mines, in co- 
operation with MSHA, the Kentucky Depart- 
ment of Mines and Minerals, and several 
private coal companies, have developed a 
set of training materials designed to 
increase donning proficiency. To pro- 
vide an empirical base for the construc- 
tion of these materials, the investi- 
gators videotaped, under experimental 
conditions, 50 miners putting on the CSE 

. . . 

'Educational psychologist, University 
of Kentucky, Lexington, KY. 

2 Research sociologist, Pittsburgh Re- 
search Center, Bureau of Mines, Pitts- 
burgh, PA. 



INTRODUCTION 

AU-9A1.3 This was the model in use at 
their mine. Each person's performance 
trial was first timed. The entire don- 
ning sequence was then broken into sub- 
tasks and evaluated (fig. 1). Finally, 
errors, interruptions, and omissions that 
occurred at each step of the procedure 
were logged. This analysis of the tapes 
allowed the researchers to target actual 
or potential problems that might be dealt 
with by modifying existing approaches to 
training. 



A NEW SCSR DONNING PROCEDURE 

Based on the initial findings, an 
instructor's manual and short videotape 
demonstration were then prepared for 
field testing under Bureau contract 
H0348040. This package presents a ge- 
neric procedure for the four SCSR's in 
common use (CSE, Draeger, MSA, and Ocen- 
co). It offers (1) a donning position 
that is easy and efficient, (2) a don- 
ning sequence that moves critical steps 
(those tasks necessary to isolate one's 
lungs from the surrounding atmosphere) 
up front, and (3) a set of simplified, 

-*See "Problems in Donning Self-Con- 
tained Self-Rescuers," by C. Vaught and 
H. P. Cole, earlier in these proceedings. 



52 



Completed First 

Task Sequence Time Attempts Time Errors 

Neck strap on 

Case opened 

Oxygen on 

Goggles saved 

Breathing hose out 

Mouthpiece plug pulled 

Mouthpiece inserted 

Nose clip on 

Head strap on 

Goggles on 

Breathing bag open 

Neck strap adjusted 

Waist strap tied 

Mining cap on 



Time to signaled completion 



FIGURE 1.— Example performance scoring sheet for the CSE. 



53 



easy-to-remember procedural rules that 
can help miners order the complex array 
of tasks needed to don an SCSR. 

An Efficient Donning Position 

The instructor's manual provides the 
following directions to the trainee get- 
ting ready to put on an SCSR: (1) Kneel 
and place the unit directly on the mine 
floor in front of your knees, (2) crouch 
so that your face is just above the SCSR, 

(3) lay your cap on the mine floor so 
that the lamp shines on the unit, and 

(4) after quickly looping the neck strap 
over your head, use both hands to don the 
unit. 

This position has a number of advan- 
tages. First, in many mines it is not 
possible to stand erect. The crouching 
position works well in any seam height. 
Therefore, all miners can be trained 
alike. Second, in high coal, crouching 
keeps the individual's face nearer to the 
mine floor, where the air and visibility 
are generally better. Third, with the 
unit on the mine floor it is easier to 
work with both hands. Fourth, with one's 
face directly over the SCSR, it is easier 
to see the unit. Fifth, the cap and lamp 
lie still on the same surface as the 
SCSR. The unit is constantly illuminated 
and the miner can see what he or she is 
doing. Sixth, if something is dropped 
(such as the goggles) the individual has 
a much better chance of finding it. 

A Logical Sequence of Steps 

There are three tasks that a miner must 
complete successfully if he or she is 
to survive in a rapidly developing toxic 
atmosphere: (1) activate the oxygen, 
(2) insert the mouthpiece, and (3) put on 
the nose clips. When this is done, the 
individual can take as long as necessary 
to complete the rest of the donning pro- 
cedure. For this reason, these "criti- 
cal" steps were placed ahead of such non- 
essential tasks as adjusting straps. The 
crouching position, which allows a person 
to let the unit rest on the mine floor, 
makes this possible. 

Simply completing the absolute minimum 
for survival does not mean that a miner 



has the SCSR secured in a manner that 
will allow enough maneuverability for him 
or her to get out of a mine, however. 
Once an individual's lungs are protected, 
he or she must then proceed to (4) put on 
the goggles, (5) adjust the straps, and 
(6) replace the cap and move out. 

An Advance Organizer 

Figure 2 shows a practice performance 
evaluation that includes a simple con- 
nect-the-dot method that helps miners to 
remember the logical ordering discussed 
above. The scheme is arranged clockwise. 
The part time, which is recorded immedi- 
ately upon completion of the critical 
steps, helps to break the procedure into 
two groups of activity: (1) isolate the 
lungs and (2) prepare to escape. 

Research has shown that when presented 
with a lengthy ordering of tasks to be 
done, what people forget is not how to 
perform individual steps but the overall 
sequence. Each of the six points in this 
advance organizer helps to cue the per- 
son's recall of the appropriate discrete 
tasks it includes. The "3 + 3" organiza- 
tion is much more mnemonic than the list 
of a dozen or so steps typical of exist- 
ing training materials. For example, it 
is much easier for a miner to remember to 
"activate oxygen" and to do this first 
than it is for him or her to recall and 
do in proper order all the separate parts 
of that task. 

A Caveat 



Of course, the "chunked" sequence given 
above assumes that the trainee has been 
filled in on the details of how to acti- 
vate the oxygen and to do all the other 
tasks for the particular model of SCSR he 
or she is being trained on. Likewise, it 
is assumed that the trainer has gone over 
details of how to care for and inspect 
the units and has discussed the storage 
plan for his or her mine. The general- 
ized sequence outlined here deals solely 
with how to get a unit on efficiently; it 
does not replace other parts of a total 
SCSR training session. When used for its 
intended purpose, however, the procedure 
has potential to reduce significantly 



54 



Performance Evaluation for 


Date 


1 . Did the miner answer the following? 




A. Name the exact place where you started working 


last shift. 


Yes No 




B. Tell me how to get to the nearest SCSRs from that place. 


Yes No 




2. Connect the dots in the diagram below to show the ! 


steps the miner took in 


donning the SCSR. DO NOT TOUCH THE DOT IF HE OR SHE DID THE 


STEP INCORRECTLY. 




Total Time (seconds) 




n. Oxygen 


Nv O 

, , ~ 1 Start 
Hat On ^ 


& Mouthpiece 


© 

Loop 




Straps 


^ Noseclips 


© 

Goggles ^ 




Total Time (seconds) 


3. After the task is completed please list any errors that need to be corrected 


and then correct them. 




Trainer's Signature 







FIGURE 2.— Example SCSR evaluation form. 



the errors miners make when donning the 
devices. 



time efficient way to put the unit into 
use. 



FIELD TESTING THE PROCEDURE 



Conduct of the Workshops 



The training package has been field- 
tested with 16 groups of coal industry 
people in workshops held in 3 States. 
The workshops were attended primarily by 
trainers and by State and Federal inspec- 
tors. The purpose of the field tests was 
to add to the knowledge of how long it 
takes individuals to put on an SCSR, to 
document the types of errors they make, 
and to improve the materials aimed at 
teaching and assessing a simpler and more 



All workshops followed the same format. 
An instructor who had helped design the 
procedure first talked about the training 
activity and discussed the factors that 
had led to its development. He then ex- 
plained that the people present would be 
introduced to five innovations: (1) a 
donning sequence that rapidly gets the 
miner on oxygen, (2) fewer steps to re- 
member to don the SCSR fast and correct- 
ly, (3) a donning position that makes the 



55 



new sequence possible, (4) a performance 
evaluation that records skill, errors, 
and completion times for critical and 
secondary tasks while helping observers 
learn the procedure, and (5) the use of a 
simple, adjustable mine simulator. With 
the aid of overhead visuals, the instruc- 
tor next outlined in detail what the par- 
ticipants would be doing. 

After this introduction, the entire 
group was shown short videotapes of two 
trainers putting on each of the four SCSR 
models while in the simulator. The in- 
structor pointed out the critical donning 
steps, reviewed the advantages of the 
demonstrated position and sequence, noted 
the times these two trainers required to 
complete the critical steps, and opened 
the floor for discussion. Following a 
brief question and answer period, the 
participants were sent to their choice of 
small workshop sessions devoted to the 
CSE, Draeger, MSA, or Ocenco. 

In each small group a trainer presented 
tips on the care, inspection, and place- 
ment of the SCSR in question. He then 
gave instruction on the proper way to do 
the various subtasks, such as opening 



the case. After this preliminary, the 
trainees reviewed the videotape dealing 
with their particular model. One at a 
time, individuals next put on a miner's 
belt, filter self -rescuer, cap, and cap 
lamp and entered the simulator, which was 
adjusted to approximately 40 in. At a 
signal from the trainer, the person in 
the simulator began to don the unit. 
During each donning trial, which was done 
with no prompting from anyone, other 
members of the group worked in pairs to 
evaluate the performance. While one per- 
son in each pair observed the trainee's 
sequence and recorded it on the form 
shown in figure 2, the other noted the 
part time (for critical tasks) and the 
total time. At the end of each trial the 
trainer, who had also been evaluating 
the performance, noted and corrected any 
error that had been made. 

Findings From the Workshops 

Table 1 presents summary statistics for 
individuals donning the four SCSR's in 
workshops in eastern and western Ken- 
tucky. No data are reported for West 



TABLE 1. - Summary of data collected from SCSR donning workshops 

















Prior 


Perfect 


SCSR type 


Test 
date 


Critical time, s 


Secondary time, s 


donning 


donning 


and site 


N 


Mean 


SD 


N 


Mean 


SD 


Mode 2 


No. 3 


sequence, 






















% of total 


Draeger: 






















E Kentucky. . . . 


1/22 


7 


17.00 


5.77 


7 


55.00 


20.78 


NAp 


NAp 


28.57 




1/28 


27 


23.89 


10.61 


27 


64.70 


29.08 


3 


12 


62.96 




1/29 


15 


20.47 


4.93 


15 


52.20 


19.18 





11 


53.33 


W. Kentucky. . . . 


3/18 


16 


16.25 


4.97 


17 


41.12 


17.09 





6 


22.22 




3/19 


17 


17.53 


6.71 


18 


59.17 


19.45 





11 


38.89 


Ocenco: 






















E. Kentucky.... 


1/22 


11 


26.27 


5.87 


11 


79.45 


26.16 


NAp 


NAp 


63.64 




1/29 


11 


33.73 


10.00 


11 


82.45 


24.11 





9 


45.45 


W. Kentucky.... 


3/18 


16 


26.44 


5.66 


15 


69.06 


25.42 


0,1 


3,3 


4 11.76 




3/19 


17 


38.64 


11.10 


19 


84.32 


19.08 





16 


47.37 


CSE: E. Kentucky 


1/22 


9 


21.67 


4.77 


9 


68.88 


17.95 


NAp 


NAp 


66.67 




1/29 


16 


24.94 


11.39 


16 


62.44 


20.91 





9 


64.71 


MSA: E. Kentucky 


1/29 


10 


17.90 


5.15 


10 


51.50 


14.35 





8 


50.00 



NAp Not applicable. Experience with 
Mode = most frequently occurring value 

more than once. 

3 No. = number of people who gave the mo 
4 0f the 17 trainees, 9 adjusted the st 

this deviates from the perfect sequence, 



this model, 
in a set where different values may occur 



dal response for their group, 
raps before donning their goggles. 
it is not a critical error. 



Although 



56 



Virginia owing to the small number of 
persons in trainig sessions for each 
unit. The table presents (1) the means 
and standard deviations for critical 
tasks and secondary tasks, (2) the modal 
response and frequency for the number of 
times trainees had donned the model be- 
fore, and (3) the percent of individuals 
who recorded a perfect sequence on the 
first trial. Since all participants at a 
workshop were encouraged to try every 
SCSR being used, there is a confounding 
factor: no attempt was made to control 
for whether an individual had just gotten 
hands-on training with the Ocenco before 
donning the CSE, etc. There might be 
some negative or positive transfer of 
training in such situations, but that was 
ignored for purposes of the present 
research. 

Table 1 reveals some interesting find- 
ings. First, it will be noted that the 
critical tasks necessary to isolate one's 
lungs from the ambient atmosphere take up 
significantly less than half the total 
time needed to get most units on. When 
it is considered that some existing 



training materials recommend doing one or 
more of the critical tasks near the end 
of the donning sequence, it can be seen 
that the procedures suggested in this pa- 
per are an improvement from the stand- 
point of efficiency. Second, even the 
simplified sequence offered in the work- 
shops is difficult to get correct on the 
first trial. The highest percentage 
(66.67%) of people having a perfect don- 
ning performance was recorded for the 
trainees putting on the CSE at the work- 
shop in eastern Kentucky. Although many 
of the errors recorded could be consid- 
ered minor, the figures nevertheless un- 
derscore the need for hands-on training. 
That brings up the third point: the 
modal prior donning experience for most 
persons in most workshops was zero. Un- 
less most participants skipped the work- 
shops devoted to the models in use at 
their operation, which is unlikely, the 
implication is that there are a number of 
trainers teaching miners how to don the 
SCSR who have never themselves had one 
on. 



CONCLUSION 



The preliminary data tabulated here 
suggest there are ways to make a more 
efficient donning sequence for each mod- 
el of SCSR. Additionally, the summary 



statistics indicate a need for consistent 
and thorough hands-on training as well as 
further study to determine the optimum 
interval for such activities. 



57 



DEVELOPMENT OF AN AUTOMATED BREATHING AND METABOLIC SIMULATOR (ABSTRACT) 1 

By Nicholas Kyriazi 2 



The U.S. Bureau of Mines has been de- 
veloping breathing and metabolic simu- 
lator technology since 1970. Breathing 
simulation has been widely achieved 
throughout the world and used in the 
testing of open-circuit breathing appa- 
ratus, but satisfactory metabolism simu- 
lation has not been achieved. This situ- 
ation required that the testing of 
closed-circuit breathing apparatus, which 
are the only type used in mines, be done 
using human test subjects. The goal was 
a machine that could accurately simulate 
both the breathing and the metabolic 
functions of a human being for testing of 
closed-circuit breathing apparatus. The 

1 Reprinted from Bureau of Mines Infor- 
mation Circular 9110. 

^Biomedical engineer, Pittsburgh Re- 
search Center, Bureau of Mines, Pitts- 
burgh, PA. 



advantages of using such a machine in- 
stead of a human being for testing respi- 
ratory protective devices lie in its 
ability to quantify metabolic input, its 
repeatability, and the lack of a need to 
deal with the vagaries of human subjects. 
The foregoing paragraph abstracts the 
contents of a report describing the 
breathing and metabolic simulators that 
have been developed and used by the Bu- 
reau over the past 15 years; this report 
is available as Bureau of Mines Informa- 
tion Circular (IC) 9110. A free single 
copy of this report may be obtained by 
writing: 

Bureau of Mines 

Publications Distribution Section 

Cochrans Mill Road 

P.O. Box 18070 

Pittsburgh, PA 15236 



1068 470 



U.S. GOVERNMENT PRINTING OFFICE: 1 987 - 60501 7/60033 



INT.-BU.0F MINES, PGH., PA. 28469 



U.S. Department of the Interior 
Bureau of Mines- Prod, and Diatr. 
Cochrane Mill Road 
P.O. Box 18070 
Pittsburgh, Pa. 15236 



OFFICIAL BUSINESS 
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AN EQUAL OPPORTUNITY EMPLOYER 









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